Have you considered using Ripple network as one of the ways to process deposit/withdrawals and to transfer funds between system users, by system users? If not, what are the drawbacks here in your opinion?
Bitstamp for instance uses Ripple and in fact, Bitstamp actually is using it instead of the "code", which they used to do. Of note, BTC-e is still using codes. Bitfinex doesn't use any.
I also would love to see Bitfinex being a Ripple gateway, they likely have other problems at the moment though (e.g. bank withdrawals being limited, still only connected to one single other exchange...) and I guess they just have put this on the back burner for some more. Ripple Labs makes it easier and easier to set up gateways too by building deployable open source gateway solutions, so I guess over time it might just be that Bitfinex takes another look and they find out that it only takes a weekend or so and then integrate.
It would be great though to have it earlier as I said, I give it only ~30% probability though.