I cannot comment directly, but several of the CS5 beta-testers had both versions installed, and have indicated no issues, of which I have read.
The only issue I've found was related to tape capturing. My Canon XH A1 footage stopped being captured when I installed CS5 as trial (However I've had it as trial for a few hours only). Once I entered the licence it started working again. This is the only thing! Don't uninstall Acrobat Pro if you do have it installed.
This could have to do with the fact that as trial some codecs are not installed. Case in point is AME CS5, it is only able to export to a few formats as trial.