That camera is about 12K USD right now... but the Hero3 says it can do 4K also. Have any of you Hero 3 owners tried to export stills? The idea of a sensor that small really getting good 4K images seems hard to swallow... but I'd be interested to see how it does at 1/30th the cost, and probably 1/30th the size/weight.
The difference in quality is much greater than the difference in price.
4K on the GoPro is a bulletpoint. That's about it.
You'll see a couple new 4K cameras next week at CES (I'll see what I can shoot while there). Expect several new 4K cameras at NAB in April (at least 3 I'm aware of). Expect the price to drop in half in the next year as the early adopters defray the cost of product dev and gear-up, just like with HD, and with AVCHD to AVC-I. Start studying now on HEVC, and get familiar with MPEG...as said here almost 6 years ago...MPEG has changed up what we can do at all resolutions. Really excited for 4K and what it offers us, when combined with even low grade glass and a medium-sized sensor.