[throwaway81523]

There was some muttering on the fossil site somewhere about supporting git format. Darcs was another thing like that, which was superior to git in most ways I can think of, while fossil has an anti-rebasing ideology that makes it unacceptable for certain types of git workflow. I don't know how that can be resolved while switching to git format. I do like integrating issue tracking with source control.

[stevekemp]

Unfortunately darcs suffered from the patch-of-doom problem, where if you were unlucky an exponentiation merge would kill all performance of your repository.

The darcs FAQ from 2012 reports it as still unfixed:

http://darcs.net/FAQ/Performance#is-the-exponential-merge-pr...

(Yes this was real, and yes we hit it. I liked the patch-centric darcs approach, but that was enough to make us migration to mercurial, then later git.)