Basically what everyone's said.
For A500 games:
- The best platform for WHDLoad compatibility (make most slaves work) is actually A1200-030.
- You need a faster CPU to handle the overhead in a few tightly coded top hits
- You need 1MB chipmem even if you run a game written for 512k chipmem. This means A500+ or modded A500 late revision (soldering required).
- You need fastmem to fit WHDLoad and WB and leave 512k fast free for quite a few games.
ACA500Plus does all it can to maximize WHDLoad compatibility however it's still not 100% which is why I don't recommend an A500/+ as a WHDLoad machine.