This is my theory based on
my understanding of how it works. I could be off base, but I've spent a lot of time thinking about it. It's hard to ask questions because you just get ripped on by the 300+ people who bought it in the group buy.
The unit is designed to receive pressure from the heads and the crank case right? This pressure is in the form of air with vaporized oil (at elevated temperature). These fumes (for lack of a better term) are then routed the the central hub type unit on the oil filler tube. The flow is aided by a vacuum pulled on that junction by a line connected to the intake manifold. The idea is that the oil that is collected is cooled at the "hub" or junction point and condensed. It is then supposed to run down the filler tube and back into the crankcase. The problem I see with this is two fold.
1) the hub is not very large and therefore does not have a very big heat capacity. As a result it cannot cool the fumes enough to condense all the oil droplets and remove them from the air.
2) (the larget problem I see) the crank case which the oil fill tube connects to is where you are pulling fumes away from and it is at a positive pressure (test this by removing your fill cap and place your hand over it while the engine is being reved). Why would the oil be inclined to easily travel down the fill tube with all this positive pressure? Wouldn't the positive crank case pressure try to leave the crank case through the AOS the same as it does the PCV valve? I think this would just be giving you another crank case vent or sorts.
Look at it this way:
The incoming "dirty" air goes into the baffle area. It then travels into the crank case and then out through the "clean" air hole. Why would dirty crank case air that goes through the PVC valve not also try to travel through that "clean" air hole as well. The crank case as a whole is under pressure right? If I turn on the AC in my house and open one door and one window, the positive pressure is going to escape out both. And from there this "clean" air goes right back to your intake... but I don't think it's overly "clean".
I'm not saying the GS AOS doesn't have an effect, I just think it is not as effective as other designs.