With regard to ecash, it's certainly a cool product, but I think it's a pale imitation of an asynchronous payment. Let's say Alice wants to send money to Bob. If Alice uses Carol's service to create an ecash token for Bob, it might seem asynchronous because Alice may go offline. But Alice isn't really the sender anymore. She gave her money to Carol and got her to promise *she* will send it to Bob. (Or rather, whoever comes first to claim it with something that is essentially a promissory note.) When that happens, the real sender is not Alice, it's Carol, and in order for it work Carol (the sender) must be online when Bob wants the money.
I don't have anything against that, I think it's cool. But I don't think it's *as* cool as a true asynchronous payment. With zaplocker, Carol never has your money. Carol is essentially a routing node between Alice and Bob, and routing nodes don't have custody of funds that use them as part of a path. I think that's cooler than a custodial model like ecash. Instead of depositing *money* with Carol, Alice routes a payment *through* Carol in such a way that Carol can only cancel it or forward it, not keep it. But after that it's largely the same: Alice may go offline, and Bob may come collect his money at his leisure. With ecash, Bob doesn't have a time limit, which is cool, but I think that's an acceptable tradeoff since the gain is self custody.
