Well, i'll start. I live in Western NY and I run my heater about 10-15 hours/month, May to Sept. I do use a cover Natural gas. At my rates it costs me about $1.00-$1.25/hr to run. I don't maintain any specific temp.
With this, and the info in my sig line you can see how this won't compare at all to your pool and area. Heating a pool, or anything, is all about the BTU's.
In the case of my pool, I can raise the water temp by 2 deg/hr with my 100,000 BTU heater. To do the same with yours, you would need a Heater with a BTU output of 480,000 BTU which would be roughly a 575,000 BTU heater (input). At that rating, yours would cost about $6.00/hr to run on my gas rates.
There are electric conversion tables to use to input the cost and energy usage to heat with heat pumps as well. I don't mess with them as electric heat in my area doesn't make much sense.
Dan