Originally Posted by DakarM
the first method is probably best. the aftermarket solutions all seem to have a "shield" around the hose. I would imagine it probably shields the air flow coming out of the hose so it's directed towards the center of the rotor.
The reason for that is because vented rotors use the fins sort of like a centrifugal fan, so the more fresh air you can put there, the more it will spin through.
BUT, if you're trying to reduce fade, the caliper is of more importance to cool than the rotor, assuming you have good pads.