I dont think so. I do all of my water changes through my skimmers, and on my 225 DSB tank and pull out between a gallon and a gallon and a half a day.Pulling out all of this "stuff" is not nessesaraly a good thing, that is one does not want things such as phytoplankton to be removed, and it does get removed, one would like it suspended in an aquarium pelagically like what happens in the ocean. I think that skimmers like yours would be unhealth for my aquarium inhabitants as a GaLLON a day is a bit much, right?
On my BB tank i dont skim quite so agressively. Its a 90 and i pull out 1/2 gallon a day.
You can follow the link in my sig to see how unhealthy the tanks look from all of this skimming. I feed my tanks nothing besides homemade food for the fish, calcium, alkalinity, and magnesium.
To be sure, ,many ways to skin a cat in this hobby and a skimmer ISNT a necessary piece of equipment to have a happy healthy reef. But quality water is, and a good skimmer can help tremendously in this regard.
To keep this thread on track..........I think it is a good idea for any LFS to keep a couple high dollar skimmers in stock. Many people prefer to buy locally and you might as well capitolize on it. And even if it isnt the exact skimmer someone wants, they at least know you can get the right size for them as a similar one is already on your shelf.