Justin, the whole point of this post is to demonstrate that a browser sniffer isn't a sustainable long-term solution. If someone reading this implements it, even if there are no missed browsers today, is the client willing to pay to have the developer go back and replace the code each time a new browser comes out? And what's the guarantee you'll even be maintaining it in a year or two so that developer can get a current browser sniffer?

Also, how does your script detect IE10 in metro mode versus desktop mode?