As another non-GHC contributor, my opinion should probably also count for little, but my experience with git has been poor.
I have used git daily in my job for the last year. Like Simon PJ, I struggle to understand the underlying model of git, despite reading quite a few tutorials. I have a high failure rate with attempting anything beyond the equivalents of darcs record, push, and pull.
I'm in exactly the same camp as Malcolm. I don't understand git, and I end up deleting the entire repo and starting again every time I try and do anything clever - something I've never needed to do with darcs. I consider the git equivalent of "darcs unrecord" to be "rm -rf", but I'm sure that's a lack of knowledge/intuition on my part. All my git dislike aside, I wouldn't worry about git and Windows. GHC on Windows already drags in plenty of dependencies from Cygwin or Mingw, both of which provide workable git binaries, and none of which ever seem to have caused a problem. The standard gui's (gitk and git gui) both work on Windows, and I certainly miss them when using darcs. Thanks, Neil