The Aqua C Remora is more than enough skimmer for a forty gallon with sump. The efficiency difference would take at least a year or more to provide a payback based on just electrical efficiency alone. Like about three years based on a cost of 20 cents per kilowatt hour. I have several needle wheel skimmers, they are OK, but nothing like great. I would place a needle wheel skimmer a little better for small, less than 200 gallon tanks. But Problems are more numerous with nearly all needle wheels than with Aqua C's small skimmers. Replacement needle wheels run around $40 each also. There are no parts but a small standard impeller pump to wear out in a Remora. Stay with the Remora until you need more filtration than it can provide. Then consider a quality needle wheel skimmer, not a cheap one. Octopus is a lower end skimmer, as are Turboflotors and Coralife. I own two Turboflotors and an Octopus, but not a Coralife.