Hiya, I'm interested in running this but I was hoping to run the PS3 version from PSN. Are there any major differences or is this fine to run?

The PSN version will load somewhat faster than the PS2 on disc and probably about the same speed as most viable emulation via PCSX2 - having said that the leaderboard is loadless so that doesn't matter.

There are some differences in what lags the PS2 vs what lags the PSN copy of it, so likely the PSN copy will lose a little bit of extra time due to that, however it isn't enough time to be a big concern unless/until you reach very high performance levels.