Tried to upgrade the software to the May 12, 2006 version linked in Scott's post at the top of the 970 forum. It seemed to work correctly in that it connected, erased, wrote, and verified the update. It did NOT however erase any of my settings (as the instructions say that it will). Am I to assume from this that the update did not work?

I'd check the version number to confirm that it applied. With the 990 firmware, the update itself wouldn't erase the settings, but resetting the unit afterward would.

The Model 970 update does not reset your settings. Therefore you are encouraged to do so following the update but prior to its first usage.

Best,

Scott