I use Debian unstable in production

It's actually pretty darn stable. The main thing is to update it frequently, so the updates are small and easy to reverse if necessary.

I do take some care. I read the changelogs and watch the upgrades for anything major. Sometimes I put stuff on hold. I upgrade my desktop first, then a test server, then slowly work across the cluster.

Then I pull really current stuff I want (Firefox 20, gcc 4.8, samba 3.6.13, etc.) from experimental.

But overall it's worked great. I haven't used testing (much less stable) in forever.