Is it really under the radar though? If you're aiming for TechCrunch front page then being in SF is probably a much better bet, but beyond that hype bubble you can still do very well. There are certainly talented people all over the country and of course you're going to save money on rent, salaries, and basically everything else if you go outside of San Francisco.
Not having ever founded a company I could be extremely wrong here but my take is that SF could be detrimental to certain startups.. If you have $x saved up to support you while you start a company it's going to last you much longer in basically any other city in the country other than perhaps Manhattan. At that point you basically have to decide which is going to be more of a factor in your success, extra time with which to build your product or physical proximity to an entrepreneurial community? Of course there's no one right answer, but I suspect that for many web-based startups the extra time and savings would be more important than the surrounding environment.
Not having ever founded a company I could be extremely wrong here but my take is that SF could be detrimental to certain startups.. If you have $x saved up to support you while you start a company it's going to last you much longer in basically any other city in the country other than perhaps Manhattan. At that point you basically have to decide which is going to be more of a factor in your success, extra time with which to build your product or physical proximity to an entrepreneurial community? Of course there's no one right answer, but I suspect that for many web-based startups the extra time and savings would be more important than the surrounding environment.