Do they test or re-code those PS1 games to see if they're emulation friendly (or to make them emulation friendly)? My PSP is hacked to emulate, but I've heard that even without that, Xenogears has trouble in every system during one of the Deus fights. Something about the PS2/3 and PSP not designed to emulate exact enough causes it to hang when it does one of its special moves, so its suggested to beat that fight extremely quickly if possible. But over-all, compatibility ratios seem to be rather high, especially for more mainstream games