Nope, my threads usually take about 2 replies to get the answer I was looking for. Must be b/c I just ask people to confirm what I'm thinking.
I'm just trying to throw some ideas out there and my very fresh opinion if I know enough of the subject to even make one. lol
As far as the types, here's the breakdown for ya flamehawk:
venturi's are like the seaclones, powerheads with a venturi valve in them squirt the water in the skimmer to make it swirl.
counter current and downdraft as I understand them are basically the same, water goes in the column at the top and out the bottom and bubbles rise from an air stone at the bottom against the flow of water.
Personally, as an engineer, I like the venturi type better. I think they have a better suspend time. Which is good b/c it increases the chance of proteins bonding to the air bubbles.