The black definitely has a big difference in image quality over the white especially if you use the native modes of the sensor - 2.7k @ 30fps, 1060@ 60fps ( not 30) and 1440@30fps.
The reasons why the native modes are best are explained here by the guy that shoots and edits the Gopro Promo Videos, Head Production Editor and our GOpro User Forum Guru Abe Kiislevitz. It's how the images are down sampled that makes the difference between modes and even the Field of Views (narrow, wide, medium)
abekislevitz.com/understanding-your-new-gopro/This is the comparison list of the current HD3 models compared to the previous GOpro models.
HD3 White 5MP is basically the same image quality as the Old HD1 (except with flat underwater lens)
HD3 Silver 11MP is basically the same image quality as the Old HD2 (except with flat underwater lens)
HD 3 Black 12MP is big step up on all of them mostly due to the 3x increased recording bitrate and new sensor.
As Rob has discovered, even the basic white camera can record awesome video in good conditions with little Risk of water ingress unlike the caseless, water resistant ONLY cameras. I agree with Rob, if you want reliability and good image quality, the white will serve you well if you use the BASIC camera features and forget about all the added BS like wifi etc. However if you want video for PRO production needs in more challenging conditions, the Black with Protune is the ultimate but comes with a huge learning and maintainance curve, not a camera for the mount and record crowd.
Fogging... It's easily prevented if you use 2 methods combined, like fog inserts and keeping your case and camera stored in a sealed lunch box half full of desiccant when not in use and don't introduce sweat on the camera when inserting it. There are many other combinations that work also.
Nice work Piros, enjoy your GoPro mate.