Earnest, I think it may still be missing an appropriate install file. I've been trying to get a very loose product feature in core that folks can use to attach recurring fees to products, though it may be best for Payflow Pro to ride along as an individual solution... seems to have quite a robust API to handle them already.

I'm still trying to weigh the merits of a system like you're using against one that just continues to enter payments for the original order for my default recurring fee handler (for use w/ the credit module). It seems your way could confuse product/order reports by showing each membership purchase say 12 times in a year, whereas my way would cause order balances to go into the negatives pretty fast. I've considered letting charges be made that don't get logged to the payment receipts table and makes a note in the order comments every time payment is collected, but then we've got no way to report revenue. Too many choices..