I've been hacking on a directory comparison and sync front end in Emacs
that uses rsync, diff, cmp, and Ediff to do all its comparison and syncing
under the hood. Its primary differentiation vs. Ediff alone is a flat view
of all the differing files in a directory tree, rather than Ediff's single
directory per session.

If you'd like to give it a try, clone the code from
https://github.com/matthewlmcclure/dircmp-mode, load dircmp.el, and M-x
compare-directories.

I'd value any feedback you have, good or bad.

Matt

-- 
Matt McClure
http://www.matthewlmcclure.com
http://www.mapmyfitness.com/profile/matthewlmcclure