As stated previously, the rev 2 PCB was for developers and was the first one to work without the debug board.
The rev 3 PCB was the general release PCB for PAL/NTSC markets and is the most common type. The Rev 4 PCB was for the French SECAM TV system, the only change being the video encoder.
I may have a list fo changes from Rev 2-3 somewhere. If it works fine, be happy.
