I have an A3000 and as much as this is a "classic" Amiga for the most part, I still have a really hard time playing older games (which I love ...) on the 3000. I am fairly adept at using degrader applications like TUDE and WHDLoad, but, I find that the games even "feel" different than they would on an older Amiga.
In light of that, I set out a while ago to build the ultimate Amiga game box. So, I threw an Amiga 2000 together, got a 1.3 ROM for it and a GVP SCSI/030 card. I can use the GVP tools to reboot the Amiga with the card completely disabled and basically play every game ever made for OCS and ECS Amiga's.
Long story short, I wouldn't even bother with the A600 (I once owned one of these and had many issues with running games on it ...) and I would use the A500. Everything will run on it as long as it doesn't require AGA, which few games do anyways.
Sorry for the long post, felt like babbling ... :-)
Hope this helps,
- Mike