Does anyone have one or have you heard much about them? No natural gas so I was wondering if electric would be cheaper to run then propane
It depends on how much you pay for propane, and how much you pay for electricity.
I am not expert, but here is my take on it. Propane can heat up water much faster, but it costs more. So, a 400k BTU heater can heat up a spa from 80 to 104 in minutes (I am making the actual numbers up, but it is relatively true). An electric heater would take much longer to do so.
Portable spas mostly all use electric heaters (not propane) and usually are kept at the usable temperature all the time because it takes too much time to bring them up to 104 otherwise (and with the cover on, maintains the heat easily).
Again, I am giving you my understanding, with not much to back it up.
We have a propane heater (the costs was minimal) for our pool and an Electric Heat Pump (much more expensive) for our pool. The thought is that we will use the propane heater to get our pool up to a usable temperature quickly in the early and late seasons and the electric heat pump to maintain the temperature (or rise it slowly). I don't want to not swim in the pool because it is too cold (during the swimming season), but I don't want to pay an arm and a leg to do so.
From my own (again, unscientific) calculations at the current propane rate where I live ($2.45/gallon), it will cost about $11/hour to run the propane heater. I can't tell how much the heat pump will cost, because their specifications don't tell me that in an easy way to read, but it look like closer to .50/hour to run (although you get much less heat for that).
We are getting a hot tub, but not one built in (because we want to use it in the winter, when our pool is closed). As I said above, that will be electric for heating, but from what I am told, with the cover on, it is able to maintain the heat for little cost (I was told