Heat Pump Water Heaters
Note
We have a Heat Pump Water Heater (HPWH).
It definitely is more efficient than an electric resistance water heater. I got it at a Home Depot "reseller" (in Atlanta - that experience was a bit sketchy - not unsafe, but I'm not quite sure of how they came by their material).
There was an issue with one of the sensors and I get email warnings from the device saying: "contact your HVAC professional", with Alarm Code A105. After contacting the factory and them sending me replacement sensors, I replaced the faulty sensor and the warning went away - this apparently is a common failure mode with this model.
On the whole, I would buy it again.
Later, I found this DOE Heat Pump Water Heater selection tool to maybe make a better equipment selection next time.