pbognar
I think dappa1's question was, if you buy in at "E", can you rollback to "A", if that particular version works better for for you, for some reason.
AFAIK,you will be able to rollback to previous versions, but will not get the extra content.
I may be completely wrong, but someone more knowledgeable will be along shortly to correct me, if I am.
So far I have not needed to rollback. Any issues that have been affected me at all (and I can only think of one trivial one) have been fixed immediately with either a quickfix, or a workaround.
I like the way this rolling update/membership model is working a lot.
Well done Cakewalk.