Hi
I'm running the latest firmware with no issues at all (well except for password on the Wi-Fi page reverting back to the boxes admin password, although not everyone seems to have that issue, plus once it is set up you don't need to go into the page again).
It is very solid on my line, and hasn't rebooted or frozen at all on the latest firmwares.
The hardware is pretty top notch (includes an RF filter as close as you can physically get before the signal goes into the chip, which I've not seen on any other modems before) so if you can get it for a good price, well worth the money.
Regards
Phil