a lot, and I mean a lot of stuff has changed since cs3. If you import cs3 stuff into cs4 or cs5, you’ll run into interpretations, color management, everythings different. For one quick example, to get cs3 and cs4 to look comparable, go to cs4’s project settings-working space-compensate for scene-referred profiles. That did not exist before.
https://technicolorsoftware.hostzi.com/