I have on my MacBookPro AC11, AC10, AC9, and AC7 installed. They all run well, but all but AC11 are used only to access older projects. AC7 is said to open back to version 4.5 which is almost as long ago as I've been using the program.
I guess they will all run well as long as MacOSX runs old programs. I see no reason why they shouldn't. My old MacOS 7 programs ran fine in MacOS9.
Of course, it would be better if the current version could open all old versions, but I can live with this. Hard diskspace is cheap these days. I'd rather GS concentrates on making progress.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1