I don't mind waiting for hot water, but I don't let the run-up go to waste. I have a five gallon bucket that I throw in the shower to collect the colder stuff. This water goes to water my plants, mix-up car wash soap, in the filtration tank for coffee water, fill the hot tub etc. I really don't like to waste water if I can help it. Re-circ sounds like a problem waiting to happen.