I tried PS3 emulation today to try GT5. After more than an hour or fiddling with it, I gave up. Long story short, the game crashes on menus about half the time. Each time it's "compiling shaders" and spikes my CPU usage. I assumed it just needed time to compile, but after several minutes nothing happens. There's a high chance it does this each menu, and given how menu driven GT5 is, I couldn't get to a single race. Maybe I'm doing something wrong, but my PC is quite toasty so I'm going to leave it for a later date.
I'm also downloading Dragon's Crown. I'm not really interested in the game, but it's small by PS3 standards, and has good compatibility, so it might make a better test.