For the initial arc diff it seemed to work. I got a commit message pre-populated with Depends On: Dxxxx.

I'm checking this out nowish. Will let you know what beasts I run into in the wilderness of the experimental branch.

FWIW, FB is using Quip for this kind of design/idea document these days: http://quip.com

https://secure.phabricator.com/conduit/method/differential.getrevisioncomments/ points me to this task, but this doesn't make it clear to me why differential.getrevisioncomments is doomed, or what I might use to replace it.