In assigning a tempo map to a guide track for the original "Highway to Hell" recording using Shift-M (Set Measure/Beat at Now), I triggered brundlefly's comment from an old thread when deciding to go back to previous areas and insert more changes. Specifically,
 

brundlefly
[...] but when you start snapping additional points in between to follow a fluctuating tempo, things can get ugly. [...]

 
"Ugly" is almost an understatement for what I am looking at now. It does follow that adjusting Tempo Map will shift the wave form following it, but what does not make sense is this:
 
--- If insertion of a tempo change at 8:04 shifts my 11:02 (next assigned tempo change) transient, then deleting the 11:02 transient tempo insert and assigning it again *should* shift all following material back to its original (adjusted) placement. But it most certainly does not.
 
As Shift-M adjusts the waveform between the set point and the previous one, what "appears" to be happening is this same algorithm is used on the material after it based on the adjusted tempo rather than the raw (original) wav.
 
Example: Add 10% to 100, you get 110, but subtract 10% from 110 and you get 99. This is the "drift" I am seeing this with the wav form in subsequent markers if replacing the first "off" tempo after an insert in prior material. It is like the wave form is adjusted, sure, but the calculations are not using the original audio each time.
 
Is there a better (or any) way to insert tempo map changes without redoing everything following it?

The issue you referenced was fixed in X1 sometime, and doesn't affect Platinum. Setting tempos with SM/BAN does not affect playback of MIDI or Audio; it just changes the tempo to make the M:B:T times land on the absolute Now times you specify. And setting more points in between previously set points is not a problem. The audio waveforms will be redrawn visually, but no actual stretching of audio occurs.
 
I'm headed out for the day, but can take another look later later if you give specific example of what you're setting, and what the result is. One place you can get  in trouble is if the first down beat isn't at 1:01:000. This can be handled, but takes some extra steps.

I aligned this to the first kick on 6:01 initially (so the track does not touch 1:01) with a base tempo of 114.76. Due to the variations in this track I found it easier to use snare hits and went back to align there. It didn't take long for this drift to rear its head though. In the below image, 8:02 was assigned to a snare hit, and the original 8:04 is marked in magenta (and is way off from the transient it was originally assigned to).
 
 
Since the timeline is marked for that segment (8:02-8:04), it seems the calculation is done to the marker insertion value, not the underlying wave file. The "new" segment is also "140bpm" which is way outside the expected 115bpm range. This creates a ripple effect if continued. Of course, audio is not affected, but the intent of this is to insert a MIDI drum track.
 
Bottom line, the original markers were intended to be aligned to transient hits. I have not seen this behavior before (in X3 or Splat) - in the past inserting a SM/BAN marker between two existing ones always left the two existing ones in place and adjusted only the "loose" waveform between the existing two. This morning it did not. This is Ipswich Build 33.
 
Another possibility for the calculation error is some insertions were removed entirely, and others removed then replaced.

The short answer is you have to Undo a 'Set' to restore the original tempo and alignment. You can't just delete a tempo change created by Set Measure, because SONAR has no way of knowing what beat to return that Now time to; it just leaves the most recently set tempo in place without regard to the later alignments. If you decide to start over, you have to Undo back to the original state or the last place you were satisfied with what you had.
 
This is especially critical with MIDI, as deleting a tempo change will change the way the MIDI plays back since it always follows M:B:T time. Audio clips that don't start at 1:01:000 and have their Timebase set to Musical will also get out of sync in that case.
 
Edit: That said, on re-reading your last post and looking at the screenshot, I'm a little confused about what you're doing. If I understand correctly, you're using SM/BAN against a click track, but that click track has Audio-snap enabled so you can see transient marker pool lines on the musical track(s), is that right? If Audiosnap is just enabled to show pool lines, the guide track and musical tracks should stay in alignment with each other no matter what you do, though they will get misaligned with the timeline if you delete tempo changes. But if you've enabled Autostreth on the guide track, it's going to get stretched/compressed when you delete tempos. I've never tried to mix Audiosnap and SM/BAN; they're not mutually exclusive, technically, but it's not something you would need/want to do in most cases.

Hi Dave, thanks for the feedback. I only used SB/BAN for what I was doing, but also didn't check when I started how "all over the place" that beat is. I ended up simply deleting all SM/BAN entries and redoing it properly, but that left me wondering if using AS is the better method? In the screenshot above, the 8:04 transient was initially aligned via SM/BAN (not AS).
 
In essence, the initial pass is more to align the timeline to the underlying audio. In this way, I can insert a drum VSTi to match the track beat-for-beat, but left me with the situation I experienced if more editing is done (and the real concern going forward). Is using the AS pool a more preferred method for this? I am not a heavy AS user, and the real goal here is to replicate the same tempo drift of the original.
 
This was more something for Sunday morning fun. In the past, most tracks are close enough to a steady beat that minimal SM/BAN inserts are required, but this one caught me off guard (I should have chose something else but it was the first tune that came to mind, being Sunday of course ).
 
Edit: This is a post with a video Karl had posted for X1 ("Sonar X1 - Extracting a tempo map the easy way"). I need to revisit this and wanted to link it for anyone following this thread.

I think I mistook Snap Grid lines in your screenshot for AS pool lines. Personally, I would stick with S/MBAN for a job like this. Ultimately, it's not a lot more time-consuming than massaging transient markers to make Set Project From Clip work as expected, and it gives much more precise, predictable and controllable results. Set Project From Clip has had an issue for some time now that it doesn't place the tempo changes right at measure beat lines which irks me, though it may not make an audible difference.
 
Off the top of my head, I would not have expected Highway to Hell to have a lot of tempo variation, either. I might have to check it out.

Hey Dave, I just sat down and did this with AS, and works well (allowing for further editing), but also has quirks in it. I had to set project tempo from clip using beats (it varies that much), and the quirk is this - unless you have specifically locked a pool parker, it does not snap. I.e., even if 17:04 is sitting on a transient (correctly), and you "Set Project Tempo from Clip" it doesn't snap the timeline. If you click 17:04 so it turns red (but doesn't go anywhere), "Set Project Tempo from Clip" snaps. This adds more effort than is necessary, but AS did the trick. (I literally clicked every snare hit in the song to do this though, and really should not have to).
 
Upside of this... no rendering is necessary, and the pool markers stay resident in the cwp (thankfully), so I could simply enable transients, make adjustments, set project tempo again, and disable AudioSnap. No muss, no fuss on the re-editing side, so the only issue is the non-snap for unlocked pool markers (which is bothersome). Edit: The pool markers only seem to stay resident in RAM, when the cwp is closed they disappear.
 
I honestly would "think" this to be a bug, since if all transients align, setting project tempo from clip (especially using beats) should nail all of the black (unlocked) pool markers too. If I didn't have to lock all the snares, this could have been done in a couple minutes easily.

Just a quick follow-up to close this to outline the method I finally chose (not perfect, but close):

1. Import and calculate generic bpm from track.
2. Slide audio to place first desired beat on a measure marker (easiest if grid is viewable in front of clips in track view). Bounce to clip(s) - this step makes life simpler!
3. Shift track view to "Audio Transient" view. Click track and open Audio Snap Palette (Alt-A) if required.
4. Click "Edit Clip Map" and move 1:1 mark to first beat. Set "Average Tempo" dropdown at the bottom-left corner of the clip to the closest bpm to calculation.
5. Move through track and align markers at the top of the clip (audio snap pool markers) as needed to align them.
6. When complete, select "Set Project from Clip." In most cases, using "measure" (from the dropdown to the right) will be sufficient. In this case I chose "Beats"
7. Issue noted - When using beats for this case, I had to click on 1/2 of the audio pool markers to turn them red (locked), then clicking "Set Project from Clip" snapped the clip timeline appropriately.
8. No render is required when Audio Snap is disabled (tempo map remains changed), but the audio snap pool markers only seem to stay resident when the project is open.
9. If adjustments are made after the project is saved/closed, the above must be done again.

I feel compelled to add that I used Melodyne Studio for this.

Melodyne can be used to align audio to the project timeline, but not the other way around which is what this thread is about.