So it sounds like either of the lights I was considering would work for me. I may try them both as I like to have access to more than one light, just in case one fails or abandons ship. The Radbot could do double duty on the bike that has no rack mount.

As for the Superflash, I've had them for a year or more and couldn't tell you where I picked them up. I don't see any holes in the casing, but waterproofness has always been an issue. In a heavy downpour, I would find that my light was off, or had changed from blinking to solid, and wouldn't respond to button presses. If I was smart, I'd remove the batteries and let everything dry overnight. If not, I'd park the bike in the living room, and after an hour or two it would just start blinking. Usually by keeping two lights going, one would remain functional throughout the ride. Now that one seems really and truly dead, I think it's time for something less susceptible to the rain.