Have these been modified in any way or are they the exact same as the PS3 versions?
its remasters so all the textures upped to 1080p, FPS is set to 60 fps instead of 30, and the game renders at 1080p. So yeah it looks a lot better, its not just the ps3 version recompiled. They also added new trophies (not part of platinum), added a new difficulty mode, added photo mode, and probably more stuff.
great set of games, I finished two days ago UC3 and got the plat for it and working on the plat for UC1 and UC2 now. I'd recommend playing the games on crushing so you don't have to run through the game twice, and maybe grabbing a treasure online guide since some are easy to miss.
Digital prices drop all the time, I got mine for $20 from one of those key sites. Its nice owning it digital since it'll be nice to go back and replay some bits after UC4.