We have a small (tiny) startup with a local community membership, and I'm the sole developer. Members are able to edit their own content. After a couple of rounds of broken IE (even 9) and the hassle of even keeping a Windows test platform usable we dropped IE support for members in favor of Chrome, Firefox, Opera or Safari. So far, no members have complained and we've been able to turn back on features that just didn't work in IE and will soon have removed every special case in the CSS and javascript. Frankly if we are loosing some hypothetical customers who insist on IE, we're better off without them.
Visitors to the site can still use IE, but we'll be working to discourage even that in our small part of the world.
We also support some of our members who are less computer savvy and for the last couple of years when we get a request for help with their local machines, we suggest switching to Linux. So far we've had close to 100% success, with users being really impressed with the live Ubuntu CD demo and having very few questions or issues after switching over. Months later we still hear about how much better their experience has been. I've heard several variations on "I thought I was stupid and didn't understand computers, but this is just easy."
And then Unity came along.... I'll save the rant for another post, but I'm really worried that this is not just annoying for experienced users, but after trying to show people how to use it, it's a real step backward for new users too.