I'm looking at going this route before I finish the basement. The master shower is the furthest point from the heater, and it takes a solid 2-3 gallons to get hot water in the morning. The math didn't make sense until I put in a heat-pump water heater. Now I average $170/year to heat my water, and the recirc should only add ~$30/year. My pipes are well insulated, but I'm in a colder climate so loosing heat into the walls just lowers my heating bill.