I may end up using QSettings, but only if I can't find time to finish IML.
One thing I plan to do no mater the format(s) chosen is to make an abstract interface. That way if someone wants, say JSON all you would need to do is make a new back end. Depending on how hard it is I could even make it plugible
I know QT comes with stuff to facilitate this but I don't know if it would work for something like this or not, clearly I need to do some research 
In any case cam4 comes first and I have little enough time to spend on that as it is
) with the current csv method as the default, different format(s) can be easily added at leisure.