Well my experience with braintree is that if your business model is innovative enough they won´t take the risk to process your payments (told personally by a braintree representative in a phone conversation, after a brief explanation of our business model). At least they are very kind, and they´ll tell you before hand, so you don´t have to waste time with all the legal paraphernalia.
A pity because the API seems really fast to implement and well thought.<p>Respecting Paymill... well we are not going to put data on the hands of the Samwer brothers right away(just in case...).<p>edit: typo.