My goal here is not necessarily to hide P2P nodes - we still need lots of clearnet P2P nodes for the forseeable future no matter what. Rather we're just using hidden services as a way to get authentication and encryption. Actually the 6-hop hidden service circuits are overkill for this application, a 3-hop circuit would work just as well for most nodes that aren't Tor-exclusive.

Ah, I see, so you're intending to use the Tor hidden services not for their original purpose (hiding), but rather as as "authentication" (someone may spoof my clearnet IP, but only I have the private key that makes this Tor hidden service connect to me, so you can trust when you connect to it it's really me). So if you trust the clearnet IP to be a friendly node, that makes a more secure connection, but if you're already talking to a bad node, moving the communication to Tor doesn't change that. I agree the six-hop circuits would be overkill for that; I wonder if the network slowdown you get on Tor will be worth the increased security? Yes, you'll be more protected from MITM, but if this is widely adopted, would the overall transactions/second the Bitcoin network could handle go down?

Brooks