[Jasber]

Just as another data point, I agree with magsafe. I've used Core Data a bit recently and haven't really had any problems with it (though I agree it could be nicer).

My huge, huge, huge problem, on the other hand, is sync. I don't want to get locked into iCloud and the idea of Apple offering multi-platform support is unrealistic.

If you offered this as a cross-platform solution + syncing I'd sign up immediately (it sounds like this might be where you're headed anyway).