You're doing real-time payments?? My unanswered questions about no-NSF/guaranteed funds are even more pertinent then... It sounds like you've either got some ridiculously good creditworthiness detection, or you're glossing over a huge issue.

As a money transmitter, I don't know how you'd get around the legal requirements to collect SSN and contact info for US recipients...

Dwolla also has "Guest Sending" - so users don't need to sign up for dwolla to send me money: https://developers.dwolla.com/dev/docs/transactions/guestsen...