Might as well start a thread for this like they have over in the 500 forum.
I've only had my 520 for a week, and I really like it. The only issues I've had so far are that sometimes the bluetooth requires me to restart on the device to work properly, and then tonights FIT file is really corrupt so I can't load it over to strava.
The online FIT tool doesn't fix it, and then I opened it in golden cheetah. It seems the timestamps are all whacky, where it should be increasing every second, but it looks like the stamps are becoming integer overflows. The data is there, I just don't know of a way to edit all of the timestamps by just setting them as monotonically increasing seconds after they start getting corrupt in the file.
Any ideas?