An Update:
WRT to the DTC issue that kept me from using cruise control the last 2,700 miles:
As I suspected, it was an issue with the size of the tires,
BUT simply switching back to OEM sizes on both ends did
NOT fix the problem. As it turns out, it was not until
after I went through all three rear wheels and both front wheels in multiple combinations with no luck that I re-dicovered an older thread in the K16 forum that pointed me in the right direction.
Within the software of the GS-911 is a function to clear the "learned" values for the DTC. My DTC value was "-15.3mm" whateverthehell that means. I reset it to zero and just came back from a quick test ride. The DTC light is gone, the cruise control works, full power has been restored, and the only time the DTC kicked in was when the front tire came off the ground going into 2nd & 3rd gear.