The one feature that makes using Sonar hard for me is the fact that changing BPM screws up your automations if they were set to depend on the time and not measures.
If I use Sonar to record audio (not MIDI), then set any sort of automation (such as a volume envelope), and then realize I want to change the project BPM of the song to roughly match what was recorded, then the envelopes all resize to the new measure time and the envelope dots no longer relate to the right times in the WAV files. I do not often have the ability to know the project BPM of material I record in advance. It is nice to have the project BPM set roughly to the tempo of a song since many VST audio effects seem to sync better if the project BPM is in the same ballpark as the actually recorded material. Worse, there seems to be no way to even scale or fix the envelope length to get it to line up again. Would be nice if you could scale them horizontally or set length by ratio, but the Length tool seems greyed out when I show just the automation track. So, when I get into this state, I have to throw away all my automatons and start over.
I also notice that if my clips don't all have the same start times, resetting BPM shifts them around so they are no longer in sync. An annoying, but simple, workaround is to just make sure that you change BPM before changing clips to have different start times. I suspect this is a manifestation of the same problem.
Sonar would be so much more useful to me if you could specify whether envelopes follow exact time or measures instead of always measures when changing BPM. Likewise for shifting clips around with different start times. Seems a reasonable option that could be made available in the preferences with the rest of the editing choices (like cut-paste preferences).