Some customers wanted a switch to turn the hot water pump off in cold weather. as in it was cold enough that some auxiliary heat was being called for. I looked at it as six of one or half a dozen of another.
They paid to run the water heater element some more or they paid to run the auxiliary heaters some more.
Under milder weather when auxilairy was not needed, I figured the desuperheater saved them money even if it stole from the heat that went to the house. Every location is different, these geos in NW Ontario were sold to save on heating bills, the fact that they air conditioned was just a bonus.
I also prefered two tanks, the geo heated a preheat tank (with no heating elements powered) the preheat tank fed their actual water heater. If the preheat tank was elevated a little with repsect to the desuperheater connections on the geo, even with the pump off it water circulated by gravity, like a thermosyphon.