People coming from the other direction (hg first), I know a lot of people who wish they could go back to mercurial, but for various reasons can’t.
Then I had to learn git. I like the model for lightweight branches in git (bookmarks in mercurial) but the step backwards in UI is still irritating. I'm used to it at this point but teaching it to others is a constant source of pain ("git checkout -t/-b"!)
It's a situation I imagine a lot of development agencies find themselves in.
I prefer git, but my team opted for mercurial. Now(since we use kiln) I get to use git and my teammates can continue to use merc.
And the (admittedly slight) gains in productivity for some of your developers is a nice bonus.
For my home projects, I used Mercurial for a year since I preferred its command-line tools to Git. When workable GUI tools for Git appeared (starting with Github for Windows), I migrated to Git.
Also, a small bravo to Fogcreek for using a screen grab from Windows. Windows is so uncool that we need some Windows screen shot affirmative action.