[dangayle]

Users that spoof their user agent are likely to either be tech-savvy people who either know what they are doing or who are hiding who they are, like a bot.

I'm more worried about supporting older users on old machines who barely know the difference between Internet Explorer and the internet than in supporting someone who knows exactly what a UA is and how to spoof it.

[WorldWideWayne]

Take a look at what Microsoft is doing with their newest mobile IE browser - http://blogs.msdn.com/b/ie/archive/2014/07/31/the-mobile-web...

Basically they're crafting the UA to appear like Chrome or Firefox.

[Cthulhu_]

But only because web developers buckled and added loads of workarounds for older versions of IE.