I'm running CS 5.5 on Mac OS 10.7.3, runs pretty good, with some caveats. In your experience, if I install the CS6 trial, will I still be able to run 5.5 in case I have problems with 6? I want to have the option of NOT using CS6 if I need to, but I'm anxious to try CS6.
Both happily coexist under Windows. I assume it'd be the same for Macs.
I'm running 4 versions of Premiere Pro on the same Mac. No trouble.