Well I thought I'd follow up after the dust finally settled.
So, out of the box my new fancy $ saving water heater.. didn't work. It made hot water, but because the heat pump part didn't work, it used resistance heating. Making it only slightly cheaper to run than my propane.
However, now after 4 weeks and 3 visits from GE, it's been running since Thursday at noon on the heat pump (it's in hybrid mode) (heat pump only mode saves like $10/year) for $10/year I'll let it's computer brain figure out which to use (it selects resistance heating or heat pump based on a set of sensors).
SO; I plumbed the system originally such that I could use either water heater, one at a time.
However, quickly realized that even set to the max of 140 degrees. this thing would not work for us. My wife and I apparently use a lot of hot water. Unknown to me, a 50 gallon electric water heater does NOT provide the same amount or temp of water as a 50 gallon propane water heater... ugh.
Luckily I did not unhook or remove the propane one.
So, I got some pex and compression fittings because the path from the one tank to the other would have required either 10 sweat joints OR one solid piece of pex. I chose the pex to bend it over, up, over, down, and then over to the propane.
So, now the well feeds the heat pump water heater, which efficiently takes the water from approx 60 degrees to 130 degrees.
Water then travels approx 15' in insulated pex, to my propane heater, which is set to the 'default' notch. It does not tell me the temp on it.
The propane one rarely runs, and if it does, it's not for very long, as the more cost effective to run electric one, does most of the work. The propane now works as hot storage, only having to keep water at temp vs. raise it's temp.
Water comes out of my sink at 121.1 degrees (Closest tap)
And lasts plenty long enough for a Jacuzzi tub, shower, then another shower.
In-fact, we've been thus far unable to actually run 'out' of hot water w/this setup.
So, in all, a hassle, but we now have cheaper hot water, and even more of it. Reusing my existing propane tank cost maybe $50 in materials. (less if I hadn't hooked it up twice). Vs. the $600 more for the 80 gallon tank vs the 50... so still overall a savings.
the air out the back of the water heater blows COLD, and I can see the condensate trap FINALLY full of water. so it's helping dehumidify my basement as well. Basement is currently 67 degrees. Efficiency will fall with winter, but basement never gets below 45... if I don't heat it. if I do, it's obviously warmer.