Yeah, there's a high degree of compatibility. The biggest barrier is just the limited number of cases where an e-class gets a wide open power selection. The Mage is the exception, and there are a number of classes, the warpriest, the cavalier/blackguard, etc where they get SOME power selections and have some that are granted by features or otherwise 'hardwired'. There are also lots of classes that get only utility choices or no open choices at all. If you factor in various MC feats and hybrid options that were published near the end of Dragon it can get fairly complicated.