Personally I get cheesed off with my ATC(2K but uses the same recording technology as the 3 and 5K) – it uses a CMOS sensor (rather than a CCD) which has a rolling shutter – when you get any sort of vibration (think knobbly tyres on pavement, or rough track) the picture starts to "wobble" like the wavey effects they used to use for dream sequences in films. Heres a vid of it on the bar mount (Rivington Rock Road/Ice Cream Run, the youtube image quality is poor even in high Q mode, the actual raw cam output is nicer but still has the wobble), its obviously better on the helmet mount but its yfairly hard to mount it securely on a rounded object, but when it all comes together nicely its great. And its very waterproof, so you can take it kitesurfing where vibrations dont affect it!