The webapp's wormhole pairing almost worked perfectly on the first test. Turned out the remotedaemon was not noticing that the tor hidden service got enabled. After fixing that, it worked perfectly!
So, I've merged that feature, and removed XMPP support from the assistant at the same time. If all goes well, the autobuilds will be updated soon, and it'll be released in time for new year's.
Anyone who's been using XMPP to keep repositories in sync will need to either switch to Tor, or could add a remote on a ssh server to sync by instead. See http://git-annex.branchable.com/assistant/share_with_a_friend_walkthrough/ for the pointy-clicky way to do it, and http://git-annex.branchable.com/tips/peer_to_peer_network_with_tor/ for the command-line way.