PS Classic titles from different region

I've been wondering for some time now if any of the PS1/PS2 titles meant for one region would work on another. I went ahead and bought Castlevania - Symphony of the Night from the US PSN store and can verify that it indeed works on a European Playstation 3.

Do note that a non-homebrewn PSP from the same region would not accept the game, since it's have the wrong region code.

Any other experiences on this?

aslong as all files are in the same place on memory stick the game should work!

PSPs have there own region but the games etc are region free so that doesnt make a difference!