it's definitely not zero. as for whether or not i'm willing to serve those people a big scary error message, i'm not sure yet. It's something we're actually going to have to come to a decision on in the next couple weeks though, this isn't a hypothetical for me.

a lot of my traffic is repeat, so we'll probably do a good campaign to push users off IE8 this fall and officially declare it unsupported in Nov/Dec.

Yeah, I didn't mean for that to come off as flip. We struggle with it too. Unfortunately we've still got 3 or 4 percent IE/XP on some sites, which feels like a lot to lose.