@Kylo... I just figured out how to make your workflow happen in SPlat in TWO different ways. It's quite simple.
Workflow 1: Parent Track
1) Go to Edit > Preferences > Project - Record then
a) deselect "Create New Lanes On Overlap" and
b) Choose "Sound On Sound" as the recording mode (not even sure that's necessary but it's what I did)
2) On any new tracks quickly open the Lanes and enable the Record Arm button on the lane (there should only be one empty lane at this point). Maybe this could even be setup as a Track Template so you don't have to do it every time.
3) Close Lanes. You really don't have to open them again at all if you don't want to and in fact for creating X-Fades the NEED to remain closed.
4) In the Track View Options menu make sure Auto Crossfade is selected (I think it's the default)
The result is you can record all your segments as you like. ALL of them will get recorded into that one lane even if you record OVER a previous take (I'll describe what that does in a minute).
If you want to create overlapped clips just select them in the Parent Track (with Lanes closed) and drag them into each other as you normally would. Your X-Fade is created automatically.
Now THAT action (creating an X-Fade) will unfortunately create a new lane and the more you do it you may end up getting more Lanes but SOnar does seem to recycle the lanes sometimes. Not sure what the circumstances are where that would happen. It does seem a little random and should be looked at by the Bakers because to me disabling the "Create New Lanes on Overlap" should at least keep it to ONE new lane for overlap.
BUT... it doesn't matter because you really shouldn't have to open Lanes any way. It just works in the Parent Track based on what I was just doing. You can just wait until you are done your structuring and flatten or just totally ignore it.
HOWEVER here is another workflow that COMPLETELY stops those extra lanes from happening and allows you to work COMPLETELY in the single Lane at all times. The only "problem" is you have to have that lane visible while editing and Auto Crossfades are done with the Comp Tool instead of forcing the fade across any overlap.
Workflow 2: Single Lane
So with all the same settings as before just record into the track. All clips will populate the same (armed) lane and if you record over part of an existing clip the new clip will "Overwrite" that section of the old one BUT the clip remains and can be slip edited out back to full size.
*Be careful though not to record over the ENTIRE old clip if you want to keep it because then it just completely gets overwritten and requires an Undo action to recover (thus losing the new clip)... so in that case just create and arm a second Lane momentarily or do it in another track.
You can drag the clips around wherever you want in the Lane and they will not cause any damage until you drop them. If you drop them to overlap another clip it will overwrite that section. At this point you can blend the clips and adjust the start/end points by just moving the split. This incurs the Crop Tool and it behaves normally EXCEPT because there are no other clips in other lanes it is purely a cropping/crossfade tool.
Sooo...
1) Arm Track and First Lane
2) Record your segments (with or without Lanes open). *Be careful not to completely record over other clips you want to keep but partially recording over them is fine and leaves them completely recoverable via slip editing.
3) With the Lane open drag the clips around wherever you like. Dropping a clip onto another or dragging it into another will make the selected clip overwrite the older clip (either partially or completely so again do not completely obscure any old clips you wish to retain). No action is taken until you "Drop" the clip.
4) Once the clip has be dropped where you want to create an overlap with another clip drag the split Left/Right to adjust where the first clip ends and the second begins. Drag up and Down to adjust the X-Fade (this is Comp tool action).
5) If you ABSOLUTELY need two clips playing at the same time in the same track without any X-Fade action (which I would personally use another track because multiple clips at once in one track sounds like crap to me but whatever) THEN you can create a new Lane and put the overlapping clip there. Both clips will be active and you can use the old editing features in the top half of the clips to edit them together.
At MOST you end up with two Lanes (and that's only if you want to clips playing full blast at the same time).
To make up for the extra screenspace taken up by the single Lane being opened you can minimize the Parent Track/Track Control area while editing. Just pretend the Lane is your track while you edit.
==================================================
Either of these workflows will force Sonar to do what you seem to want. Admittedly the fact Workflow 1 does create Lanes on X-Fades is a little weird and I think this might be a semi sort of bug or unintended design "flaw" (it should obey the Overlap rule set in preferences) but you shouldn't even have to be opening Lanes. I do think it might qualify as a Problem Report though because it does not seem to work as it should while editing and if it was only intended for Recording it shoudl be expanded to editing as well.
Workflow 2 requires Lanes open while editing but ONLY while editing and does pretty much exactly what you seem to want. The fact a lane has to be armed seems really inconsequential compared to how much you seem to want this style of tracking/editing.
In BOTH scenarios it really seems like WAY less work/hassle/confusion than how this would need to be done with Layers. Layers were insanely unpredictable IME and demanded a lot more post tracking futzing about. With both of these workflows, particularly the 2nd one, you can at least be certain of what's going to happen to the data.
After messing with this a bit and seeing how insanely reliable/predictable/easy it all is I cannot see how your rather simple tracking/editing needs cannot be accomplished without issue (and by simple I don't mean that in a bad way... it's just not a complex workflow compared to the spazzo crap I do).
It just may be slightly different. If the problem is "It's different, therefore I don't like it" nothing can be done except to move back to 8.5 as you track and edit. Maybe SPlat can be your mixing environment if you find any value in it at all. I also really don't think another DAW is going help much because they all seem to have elaborate editing/layer/lanes schemes. I could be wrong but it will likely be quite different than even the new Sonar.
For me though, as easy as that all is (it's very old school/traditional editing... almost like tape splicing) the proper Comping/Lanes workflow is just WAY faster/easier for me and allows me to REALLY do some crazy stuff that would have taken me ages to do before.
Anyhoo... I'm mostly posting this because other people HAVE apparently gotten something out of these posts. It would be nice if you gave these things a chance though because it's not nearly as backwards and cumbersome as you seem to think.
IIRC you just recently updated from X1 (layers). There were mountains of these threads at first before people started figuring it all out. One COULD say that "Oh those people just left... that's why no one complains anymore" and some people DID give up and move to other products (or stick with the old ones) BUT many many more, who were unhappy (quite vocally in some cases) eventually gave all this stuff a proper go and now like the new tools/methods way better.
I've given you (and others) lots of stuff to try/learn/experiment with. If you just give some of it a go and muscle through some of the growing pains (like we all did) you might see the benefit of these workflows.
Layers are dead and I seriously doubt they are coming back. Even if the Bakers had any interest in bringing them back at this point it would be next to impossible without destroying a bunch of other stuff. They just would not fit into the program anymore and it would likely cause a buttload of bugs.
Again... good luck with whatever you do.
Cheers.