If you get the ACA630 you would be wise to also get the A603 and Indivision ECS to take full advantage of the faster speed. There are hardly any OCS games that take advantage of the 030, but some of those 3D AGA games have the option of using the Grafitti card, which was a Chunky graphics output in 256 colours and is emulated in the Indivision ECS. Also, through a new direct-video mode (which may or may not be developed further into an actual RTG mode) it's possible to play DOOM in 256 colours on the A600 very smoothly. It has been shown running in 1024x768 in 256 colours on an A600 with those three expansions. Hopefully we will also see a Shapeshifter driver for this new mode, so we could run all those Mac games at full speed too.
As others have mentioned though, since Amiga games generally got their timing from the chipset instead of the CPU, they don't go all crazy-fast when played on a more powerful CPU like a lot of old DOS games did.
