That's impressive. Very good information and something I've been interested in gathering for a while.
As far as a safe mode you might make a wrapper around your application to detect a crash and immediately come up with a crash response in addition to a "Would you like to try in Safe Mode?" That would likely get much better response as the user is already frustrated when it crashes and if they have to actively do something in order to try again they're less likely to do it.
I would love to have a system like this available for any jME user to deploy in their game and be able to gather statistics on a much broader range…it's something I've been considering writing for some time.
To sum up, GREAT JOB and thanks for sharing the information. 
Thanks for sharing this information Petter. Three rings uses a similar system to detect crashes and such on Bang! Howdy. There numbers seemed a little worse, but then again, their main audience comes from Puzzle Pirates - probably a much lower end audience.
We definitely want such a system in jME core; if nothing else, it would make collecting and compiling compatibility information a lot easier. Any such code donation would be helpful to the community in general.
Thanks for the info!
This really is usable to see how cross-platform jME really is compatible! 