Hmmm it seems the Numiko thingie does much more than a PID controller. In one unit that you can hang in a pot, it circulates AND heats. That thing is awesome I would definitely cash up for it if I was building something.
You could recirc your mash or sparge water and maintain temp, with the circulation taking care of stratification.
You could assist a stovetop boil and probably manage a full 6 gallons. This could be the future of small batch electric brewing
I hate having a separate pump and/or heatstick and this could eliminate both and look cool and phallic at the same time! That's a win ..