My chill time to around ground temp is roughly 20-30min .
I remember the initial question: Really no different than running wort through an immersion chiller except, because of how it's made, an immersion chiller is likely easier to clean. I'd not be too worried about sanitizing - you'll sanitize it when the 200+ degree wort hits the metal. You just might have some dead space or crook where something goes off and taints your beer. No different than running wort through a counterflow chiller, though. So it should work if you can keep a big enough heat sink for the chiller.