Mmm... so from what u have said, that means the needle wheel actually suck in air and water before the impeller and the impeller with the speed of the water will "chopped" the air and mix the 2.
As for normal venturi, only the speed of the water will "chopped" the air.
Basic principle of differential pressure still the same.
If the 2 work at the same efficient, then I suppose using a venturi is good enough, right?
By the way, with the same specification, which one is cheaper?