Osie, you have to run the pump when you are using your suction cleaner and that uses a hell of a lot more electricity that my electrical one. I was very lucky cause I bought it off of the seller when we bought the house so the cost was only 500€. No need to backwash after using it either. Our Dolphin 2001 does the bottom, walls and cleans the waterline too and look just like a psyclodelic tank to boot
Common to both is that you can't swim with them in the pool or you will stir up the muck that you are trying to get rid of. I just chuck ours in first thing and it is finished in 6 hours and quite often doesn't have to run the full time.
As has been said, if you are buying new then they are a lot more expensive, but I wouldn't swop mine!
Never forget that you are unique, just like everyone else.