The CHDs for CPS3 are relatively small, SF3 is just about 65MB.
This really is a great accomplishment by the MAME devs. I'm not really interested in the games, but it is great that they have finally 'cracked' a system like this.
That's great. You don't need chd files to play. I downloaded emulator and SF III rom, it plays very good not perfect yet as ElSemi said. Emulator has no triple buffering option. It will be perfect very soon.