I have now upgraded to PR1.1, reluctantly because of the problems reported in this thread, and I'm now surprised to have no such problems. WiFi connectivity remains even after over 2 hours of idleness, and nothing seems to have deteriorated otherwise, as far as I can tell. My experience is based on a Netgear WGR614 at home, and more professional hardware (don't know exactly which) at work.

This probably doesn't help those who are encountering problems, but perhaps it's good to know for others who are scared away from an upgrade that the problems mentioned above are not completely general. I must say that I'm so far very happy with the new firmware.