Lessons learned from our recent switch to GitHub Enterprise
dev.hubspot.com
dev.hubspot.com
We could have easily paid $300/yr ($25/mo) instead if we just used the normal Github site and had a better experience (they were constantly shifting things around to avoid the 20 user cap), but the company IT was adamant on bringing anything in-house that could be brought in-house.
Github is great, but there are very few situations in which Github Enterprise really makes sense, IMO.
I will say though, there have been a ton of improvements in Github Enterprise. We rejected it after getting a trial six months ago, and gave the sales team a huge list of problems (it was kind of disgusting, actually). Since then they've actually addressed the vast majority of our list (certainly all of the high priority things), which prompted us to look at it again. We're pretty happy with that decision.
That being said, if you're too cheap to buy licenses for all of your staff then you shouldn't use the thing. That's not a Github Enterprise specific issue though.
I do agree that its quite expensive however, this is why the company I work for chose Gitorious instead of GH:E with 300+ seats.