At a later stage company (post A or B round) you will probably have a similar work-life balance than at your current gig. But if you are thinking about doing an early stage startup you should be prepared to "work" around the clock. Most of my friends working out here have to be available 24/7 and work well over 50hrs a week.

You will also most likely make more money outside of Silicon Valley by being able to save more of your take home pay.