(Also a plumbing supply guy)
Meh; the recirc pumps that go in the outflow of a water heater do give you instant hot water, however it does come at a cost however.
Without getting too technical, the way they make a hot water "loop" is by installing a valve on the furthest sink from he heater. You basically connect your hot water line to your cold water line. The results are instant hot water, and your cold water won't be cold, it will be warm or hot.
Your best bet is to skip the recirc pump all together...wait an extra :20 secs for hot water. That is the most efficent way to get hot water and you don't compromise your cold water.
Have you seen the Navien A-Series? It has a built in mini-tank for recirculation purposes, doesn't use the Grundfos Comfort System style tee-valve at the furthest fixtures. It's a true recirc system.
Obviously that requires the ability to either install a loop or have one existing already.