Just tested one of my favourite games (Turrican) on the ACA500+ACA1232 (68030/40/128mb) and compared to my A1200 (68030/40/32mb) it runs about the same, slight slowdown when the rocks are falling and you use the beam weapon to blow them up but not a game breaker, it also takes 14 seconds longer to get into the game after pressing fire and the game screen appears, takes 3 seconds on my A1200? It's all preloaded and requires 1mb chip which I now have. I also have to use NOAUTOVEC (set that in WHDLoad.prefs) as I got an NMI error when exiting the first level (Registered WHDLoad 17.2). This is just 1 game I've compared to the A1200 though and the AGA chipset on my A1200 probably helps the game run better compared to ECS on my A500.
Have also tried about 14 pre-installed WHDLoad games on the same combination of ACA500+ACA1232 and all of them run fine and can quit back to WB in every one so that's a plus, don't need NOVBRMOVE like on my A1200 and MX1230! So overall this has made my A500 into a proper games machine or poor mans A1200 if you prefer