New Rover at day 5 & 73 miles: the LCD turned itself off a couple of times during a ride, then the speedometer stayed at 0 and the odometer didn't increase above 73. All else fine, I sent Rad an email, then the ride continued.
Within 90 minutes Rad tech support responded, asked for a video, then confirmed that it's the speed sensors that failed, they're in the motor, so the motor needs replacing. Techs offered to ship it to me when they're back in stock (next week we hope) and gave detailed instructions for the replacement.
Here's what impresses: they will ship a whole new rear wheel including motor, to make the swap easy for me. And, they don't want the old motor/wheel back. (We live 150 miles from Seattle.)
That seems like a quick helpful and fair response.
Off topic: We got a Mini for my wife. She's shorter, couldn't ride a Rover, but the Mini fits her well, with seat post at lowest position and the somewhat thicker Cloud 9 seat swapped in for comfort, and reduced front tire pressure for softer ride. The two bikes are well matched for speed (she weighs 50# less than my 160), which makes biking together easy. 15 miles today on hilly terrain, she could take it easy with electricity when I chose to select pedal workout settings.