"Smart" Hot Water Recirculation Pump

Anyone install a hot water recirc pump on their house? Specifically with a tankless unit? I'm considering a regular timer-based pump like this one to be used with a smart outlet (WeMo, Amazon, etc) where I can leave the pump on at all times but use the outlet to control when it circulates. I could program it to come on and circulate at peak times as well as turn it on/off for instant use as well or longer periods of inactivity put it in a "vacation" mode.

We have to wait 3-4 minutes of running the shower/faucet for hot water at our house and I wonder if I could be saving more water by using this pump in a smart home setting.

Thoughts/experiences?