OK I think I have thought of an elegent? solution for the which format problem.
I will modify the GameBase scripts to detect which formats is available and select automatically the appropriate file. e.g. If it only finds an IPF for the selected games then it will use that. If it finds both an IPF and an ADF then it will use the one selected as the default by the user.
How does that sound? I think it's a workable solution and easy enough to implement.
I must thank everyone for their input so far. It's brought up many issues I hadn't thought of yet. It's slowing things down
but I'd rather make sure everything was right before spending too much time adding in games. So keep those opinions and comments coming