I owned and briefly used a very similar German-made device called the Axbo:
http://www.axbo.com/axbo/CMS/CMS.aspx?Language=EIn my experience, it actually didn't work at all.
I suspect one main problem was that you could only set the alarm to wake you up within a 30-minute window, which meant there was a fairly high probability that the optimal point in your sleep cycle would occur before or after the alarm (given that the average sleep cycle is 60-120 minutes).
That said, it's one of those ideas that just sounds so compelling (Circadian rhythm!?! Sign me up!) It could work, the Axbo execution just didn't cut it for me.
I actually know the Wakemate guys, and I'm really anxious to try their product. I hope it works! For their sake, and for all those sleep-deprived hackers out there like myself!
One question I have for HN, though, is: given their supply chain troubles and the fact that, for all we know, their product may or may not actually work, what do you think about pre-selling a brand new product? Is it ethical? Is it advisable from a long-term strategic perspective (e.g. does it create the wrong expectations settings for your first users?)
I'd be particularly interested to hear from Wakemate!