One thing I've always found amusing is the diaphragm pumps are rated gallons per minute....when you do the math, most of them come in around 200 gph....
You make a good point Scott. The numbers don't lie but in the case of a wash down pump, you are looking for pressure as opposed to flow. A bilge (impeller style) pump is concerned in getting that excess water out and doing it fast (somewhat anyway). That again is a compromise with the Bait Master. It flows less and uses more current :( to do so but it also puts out enough pressure to wash blood, guts or chicken bits from the deck. 
This is all true, and as you said when the discussion began, its a function of what you need. As a for instance....the Tampa style Dorado-clone baitwells.
They use a standpipe as a drain. They'll hold 35 gallons...but use a second, shorter standpipe, they'll hold whatever you want. A half day's fishing, 20 gallons is a gracious plenty....that Shurflo Baitmaster would be ideal.
