I've never played a 1-6m-2-5 progression; I've always played 1-6m-4-5. I can't imagine playing an "A" when you're in "G" in those Franki Vallee songs. Perhaps you mean 2m? If you just use "2" when you mean "2m" what do you do when you REALLY mean "2"? There are songs that use the "D" chord in the key of "C".

Alex