[wstuartcl]

I don't think I would call the services problem the "MitM aspect" -- that is literally the largest point of value an ssh connection gives you -- its primary reason for being used is to stop MitM snooping/collection and takeover (of traffic and auth). Like most all of ssh's design is specifically crafted to reduce the risk of MitM. This offerings design basically tosses that out of the window.

* You hand over the keys to the castle (multiple keys or not -- thats irrelevant) * You specifically route traffic through a midpoint that by all means has access to inspect the traffic. You have to trust both that the operators of the service will not do this AND that there is no compromise of the service with no way to verify.