Well, I've now gotten it to work.
The problem was that I had missed a digit in my RTV serial number. It appeared to work with this invalid serial number, but would not complete. Once I changed to the correct serial number, the same steps were performed when I did the connect, but each step now took longer, and the process completed without error.
I now suspect that with an invalid serial number each step of the data transfer process was attempted, but no data was transferred, then it aborted at the very end. This was a bit misleading since the guide update steps *seemed* to be happening when they really weren't.
I will write up my beta experiences and post them separately. I made several missteps driven by bad assumptions on my part which better "how to" documentation could avoid for other new users.
P.S. I'd still like to know how to clear the guide data on an RTV.