i use them. i'd say i get a 75% increase in flow from each output. But i'm using a sequence barracuda on them now, not pressure rated. So i just bought the sequence blackfin 3500 to replace it. It is pressure rated and should boost the eductor output by 2x +.
Keep in mind that you're not pulling more water through the pump by installing these. You're jsut augmenting the pump output with water that surrounds the eductor head and gets pulled through the pressure bell along ith the pump output. Think of it as a kind of venturi for water.
Also, if you search ebay for Eductors, you'll find the same item from china for 1/3 price. I ordered six of them from there.