Definitely not transferrable between car models, it stays with the car.

I have an A129 Pro Duo, and even after a warranty replacement, it's a complete POS. It constantly crashes and stops recording without even a beep, and the only "fix" is to format the SD card every two weeks (I have one of those San Disk high endurance cards, and got a second one because I thought it was faulty). There is a feature to prompt you to do so every two weeks, but it nags you again when you reboot even if you did format it unless you go format it yourself in the settings, so even that's broken. Otherwise, the video is very nice, and the hardwire kit works well (though it did fail once and was also replaced under warranty)

I'll probably be getting the FITCAMX for my K4 Hatchback when it arrives.