Well, that's a horse of a different color. I only saw the messages on Seller Central and never bothered to research it. That's my one new thing learned for today!
According to the marketing material they provided me when they made their presentation (2+ years ago now) they claim that BillMeLater bears all credit and collections risk for authorized transactions and that the transactions are, from the Merchant standpoint, identical to credit cards.
The other 20+ pages in the packet all seem to involve how much better their conversion rate is, how there is less fraud, etc. true marketing and sales material.
Personally, BML doesn't sit right with me. It seems shady, somehow. Granted, I've never used their services as a consumer or a merchant, so my feeling entirely unqualified. However, I honestly do not know a single consumer/retail customer who uses it (...by this I mean personal acquaintances) and our wholesale side extends credit directly, so no use for it there.