I have both the 6500 and 6501 models. The 6500 is mounted on my MTB with a wired mount (wireless gets all screwed up from the signals from my SmartShocks) and my only real beef with it is that it doesn't handle multiple bikes. I later got the 6501 (wireless) to rectify the problem which I use primarily on my roadbike. In response to the criticisms:

I've never accidently stopped the computer. Perhaps because my hands are smaller and I don't grip where the buttons are.

I prefer 24hr format and every timepiece that I have which supports it is set up that way. I'm actually annoyed when some devices don't support 24hr format.

There is an autostart feature. You just have to enable it.

The freezing gear display is most likely due to corrosion in the contacts either on the hoods or in the bottom of the mount where the wires from the brifters connect to the harness. Remove and clean with contact cleaner to solve the problem.

I admit that there's a lot to the menus and sometimes I'll cycle past thye display I actually wanted to see which requires me to go all the way around again but once you understand the "organisation" of what goes where, it's pretty easy to navigate.

I have had erroneous readings before but I believe they are the results of passing over traffic sensors which put out pulsed EM signals ala a metal detector.

Overall, I've been pretty happy with my FlightDeck. There are a few things it lacks that would be nice to have such as HRM, altimeter, logging, data uplink, etc... but as far as essential functions go, it's got me pretty well covered. I have a tad over 6000 miles on both my 6500 and 6501 each.