After reading that there was such an issue with PS1 games with the later consoles. I decided to test out all 32 PS1 games in my collection. The answer actually surprised me, I only had problems with 1 actual disc Pro Pinball and that was on the PS3. There were one or 2 others but the reason they did not run at first was that they were dirty. Once clean I had no such problems.
I think the real answer to this compatibility issues you read about is this...just try out the disc (but make sure it is clean) and see if it works.
