The experiments with the different fuel types were done with one of the diesel heaters. I'll be ordering a gasoline one, so it should be fine. We all do know that there's just plain more energy in diesel than there is in gasoline than there is in ethanol. However, I will still prefer to be heating with something that I could practically drink.
Jarkko just made a post on his experiences with ethanol at his personal blog. http://kwsaki.blogspot.com/2016/01/heating-my-evs.html
I also spent some time on the phone with a friend yesterday, who is an expert in ethanol. He's made thousands of gallons himself from scratch. After speaking with him, I really don't have any concerns about it. He also said he would donate 5 gallons of pure ethanol for me to start with. (E98. It's 98% ethanol. It has 2% of other things in it, mostly to keep people from drinking it!)
As Sandange said, I expect that even if the ethanol has fewer BTUs, it still would be a huge jump up from the existing heating system. I also like redundant systems. Installing the fuel-burning heating in ADDITION to the original electric means that heat is still available if for whatever reason the fuel-burner isn't working. It still maintains the electric pre-heat feature. And a person can still use the electric only heat on short trips and/or not as cold weather to reduce fuel use.
Seems like a Hybrid Heater System has lots of advantages.
The downsides are
Cost: I have to buy the heater and install it.
Fuel Cost: I would have to buy fuel. But I shouldn't use much, so it's a very small cost, especially compared to gassing up an entire ICE vehicle.
Noise: The heater isn't as quiet as the electric, but with the radio on and the windows up, so what? Keeps us from running over all the blind pedestrians anyways.
Any other downsides? Takes a little time to fire up and there can be smell or exhaust issues, depending on the fuel. Again, ethanol should be the least offensive of any that way.