I was just about to ask why we don't see anything like that on the market! Carnot heat pumps are about 2-3x more efficient than a straight resistance element. And it would essentially do cogen (AC) in the summer, too. The unit in that photo looks far too small to be effective, though. My guess is that the average household simply doesn't use enough hot water to justify the cost.
As for the condensate pump option... water tanks are all required to have catch pans and drains, and they're ALL properly maintained, right??
