It's only been a week and Jack is totally on board with the "don't wake up till your clock is green" rule. He took to it immediately - in fact, I thought it was a fluke the first few days, but it's been a week and he's still sleeping later (or at least he's quiet). I've even moved up the wake-up time 20 minutes (and will do it again tonight) in preparation for the time change next week, and he still won't make a peep till the clock turns green!
Awesome. I highly recommend it.
Re: FYI, the Time to Wake clock is AWESOME.