The idea is nice but it's easier to stick to big, bad Microsoft. Firefox has had its share of releases due to security lapses. If you know me, you'll understand I've never been one to beat a drum against the Redmond corporation.
Really what's the point in running to install an open source program when the commerical one comes at no extra cost? I guess it just fits some people's need to root for the underdog but it must not fit into my why-bother attitude.
Still there are thanks to those who innovate as, eventually, Microsoft incorporates those 'new ideas' and this makes someone else's innovations standard. You can get a view of what next year's Windows will include by the way of local computer search. To boot, they've added tabbed browsing which is very convenient. It may even change the way you use the web.