Well, the uc_payment_credit table is deprecated. I'll be removing it altogether when we move on to 2.0. The main reason is that there's no good reason to ever query against a CC table except to load data up with an order. Furthermore, I was having to encrypt, store, and decrypt the various fields separately. Since the order object has a data array that automatically gets serialized/saved and loaded/unserialized with the order, it just made sense to move the data. It wouldn't be feasible to try and handle saving/loading differently for normal and debug modes.