The dynamo hub is on. The sidewall generator is off. The transfer of power was orderly and peaceful. The procedure was gratifyingly easy compared to some jobs that seem like they'll only take a few minutes and end up at midnight.
The dynamo bracket left a nasty little dent in the seat stay. That's an unfortunate souvenir. For the most part, though, it was a great experiment that led me to take this step. I haven't road tested the rig yet, but it works well on the stand. The power is a little jumpy at first up to about five or six miles per hour (according to the bike computer as I spun the wheel). This may improve as the hub wears in.
I like that I can turn it on and off with the switch on the light. I like that nothing wears against the tire. And, of course, power is continuous for as long as I want to ride. There will be no dead weight of expended batteries. The hub is heavier than a regular hub, but any light system requires adding weight.
So...now I just have to go ride.