I agree this forum is an incredible resource.
There is a SOA document detailing ECU reflash for both Cruise surging on downhill as well as Cruise "shutting off". I just had this done yesterday and I now have a much better behaved cruise control and now I no longer fear hills!
I have not experienced the shutting off much at all since the first ECU reflash I had about 16 months ago. However I would have expected the cause to be something mechanical instead of firmware. Either way at the moment it is not causing me any problems.