Jeff Wisnia wrote

...if you have to have this, I'd add a tankless unit in the bathroom.

They cost a lot and keep a small amount of water hot all the time.
You might compare the capital and energy costs of the tankless and
Taco solutions, with a motion detector that moves hot water for 30
seconds, using actual numbers.

Yes, but if it's in a john, howya gonna keep that motion detector from
causing it to waste energy for 30 seconds every time you go in the to
take a leak?

You aren't, and the pump would only run long enough to warm the pipe
to the distant fixture, which might be less than 30 seconds. I suggest
you compare that energy to the standby energy used by a typical tankless,
over a day, using actual numbers. This might require an actual phone call
to an actual tankless manufacturer. It's my impression that most tankless
heaters keep a small volume of water hot 100% of the time, so the standby
loss is not zero, and it may be more than the energy lost by pumping a
half-gallon of hot water 6X(?) per day.

Then, you might compare the non-recurring costs.

Nick