Try inserting a new Drums bus and a new Master bus  (call them Drums2 and Master2), then re-routing to use those instead of the old ones. That fixed it for me. There's something definitely weird here. It would be good to send your template to Cake and report the problem.
 
Cheers, Peter.
 

Its not what you think. The levels are the same because you have all the faders at unity. (thats what really matters) What is different is the readout of the meters because they are using different scales. You had a scale that was not using the full range of the meter readout on the buss. Thus it seemed to be lower when it wasn't. Setting the meters to the same scale will use the same range and they will readout the same. Keep in mind that when I loaded an audio file into your project I got the same results with the same differences that you did. I then checked the scales and when I made them all the same all the meters agreed. Its confusing if you are looking at meters that are using different scales. Sonar also lets one change the ballistics too. Its best to keep everything the same and the default unless you have a very good reason to change them.  
 
From the manual page 2088
Meters. Use the submenu to specify various options for track, bus and mains meters. The submenu contains
the following options:
Track Record Meters. Show/hide track record meters.
Track Playback Meters. Show/hide track playback meters.
Bus Meters. Show/hide bus meters.
Mains Meters. Show/hide mains meters.
Reset All Meters. Clear any clipping indicators from all meters.
Record Meter Options. Meter mode (Peak, RMS, or Peak+RMS), meter range (-12 dB to -90 dB), Show
Labels, Hold Peaks, and Lock Peaks.
Track Meter Options. Meter mode (Peak, RMS, or Peak+RMS), meter location (pre fader or post fader),
meter range (-12 dB to -90 dB), Show Labels, Hold Peaks, and Lock Peaks.
Bus Meter Options. Meter mode (Peak, RMS, or Peak+RMS), meter location (pre fader, post fader, or
pre fader post effects), meter range (-12 dB to -90 dB), Show Labels, Hold Peaks, and Lock Peaks.
Mains Meter Options. Meter mode (Peak, RMS, or Peak+RMS), meter range (-12 dB to -90 dB), Hold
Peaks, and Lock Peaks.
See:
“Using the Console view” on page 2093
“The Console view interface” on page 2066
“Customizing the Console view” on page 2089
“Console view” on page 2064
Note: Additional audio meter options are available in Edit > Preferences > Customization - Audio Meters.
 
The default meter range is from 0 dB to -60 dB. To change the range, right-click on the meter and choose a new
range from the menu.

PeterMc
Try inserting a new Drums bus and a new Master bus  (call them Drums2 and Master2), then re-routing to use those instead of the old ones. That fixed it for me. There's something definitely weird here. It would be good to send your template to Cake and report the problem.
 
Cheers, Peter.
 

Did you check the meter scale?

Good stuff, sir. I just revised my post above you. The metering aside, the readout of peak in each bus is different. I'm going to try what Peter suggested, resave the template to a new name, and bury this one so deep it won't register a scent to a bloodhound. Awesome sleuthing, gents. High praise for you all indeed.

It totally worked. Thank you, peter. I will put this one as solved, then straight to bed.

Yep, all meters set the same. I don't think this is a meter scale issue (except the roundoff in narrow strips). Also, pre or post fader confuses things. I think the buses in that project are dropping the volume by nearly 3dB, almost like a volume envelope got stuck (I did add a volume envelope then delete it to check this, but it didn't help). Pre fader will therefore see a higher signal than post fader, but that's not causing the volume drop, simply either displaying it pre or post the bus volume drop.
 
Cheers, Peter.

The pic shows even with lesser fine reporting the level output is now consistent. One issue down, one to go...
http://i156.photobucket.com/albums/t19/jshep0102/FIXED%20METERS%20YEAH.png
 

I checked the project and found:
 
1. Drum bus has Volume set to -2.9dB in Offset mode.
2. Master bus has Input Gain set to -2.5dB in Offset mode.
 
Resetting those to 0dB solved the problem.
 
Incidentally, the Verb2 bus also has Volume at -17.8dB in Offset mode, and the Leads bus is outputting directly to Main Outs.

In other words, your initial reply and the first one to the OP was correct but never checked, haha :)
Well I learned a lot about possible causes and solutions in the meanwhile!

Good catch brundlefly - you did suggest this earlier but the OP thought there was no offset. I've never used this mode so didn't think to check. I've learnt something (again!)
 
Offset mode seems dangerous because the effects are hidden, and presumably could be set accidentally. Didn't there use to be a visual indication that an offset was set? Maybe a small + or similar? Perhaps the control could be colored differently (e.g. red) if an offset is active.
 
Cheers, Peter.