IE 9 is really solid. IE 10 is pretty amazing, IMO. Not supporting IE 6-8 makes a lot of sense to me. But blocking IE 9 and 10 users seems silly. 

It's a shame Microsoft didn't make IE 9 work on XP. That's a huge hole for Microsoft and leads to problems like this. Leaving half of the Windows world behind is going to haunt you all for years.