I have a potential solution that would be easy to implement without having to risk modifying any existing code (i.e changing the current MBT implementation).
Basically Sonar could allow you to add another timeline format along with the presently offered MBT, HMSF, etc. This would be displayed along the timeline just as you currently do any of those other existing formats. Any combination of these can appear, just as we can do with MBT, HMSF, etc.
I'd suggest a name like OMBT (for offset MBT). And the offset is a value stored per project somewhere in the preferences.
The advantage here is that the internal code that supports the present MBT implementation would not need to change. Of course this only changes the timeline display in the tracks and not in the other windows (like Event View and the dedicated Piano Roll etc.), but in those cases they could include the OMBT as well.
At least it would help with those infernal calculations when comparing the DAW readings to some printed music. I may be a maths major, but I was never very good at arithmetic ;-)