I hope it's ok if I bump this bug report. It's been almost a month since I
reported it and I haven't received any feedback since. 

Nothing really new I can report as such otherwise. The problem still exists,
the driver crashes regularly. I noticed a certain possible correlation with
usage: When I'm working on the computer, the problem may happen several times a
day. When I'm not touching it, it may take up to 2-3 days for the driver to
crash. 

Sometimes logging on through ssh and restarting the desktop manager (lxdm)
helps already. But most of the times, only a reboot solves the issue.