Those articles were reference internal vane orientation... The forum link was to the racing brake forum where they said exactly that, the slot on the outside doesn't matter but ALL CURVED INTERNAL VANES must run with the vane angled towards the rear for proper operation. I have a feeling they know a thing or two about brakes.
Right now his rotors are opposite to that. It just makes good sense when you think about it too, sucks air from the center of the rotor, through the hot rotor and out the edge away from it. If it 'was sucking air in' as apparently the Z1 tech suggested, it comes across the hot rotor to the inside and goes... Where?
Edit:
From the first link I posted:
"Rotors with curved vanes, however, are directional and must be positioned properly to achieve full heat dissipation. With curved vanes, the rotor must be mounted with the vanes angled rearward, which results in a centrifugal pumping action. This causes hot air to be pumped from the center area outward. "
From the second link:
"Rotors with straight or pillar vanes are non directional. Direction of cross drilled or slotted rotors can be installed on either side as long as the front and rear match.
A curved vane rotor is directional and must be installed as left and right. The vanes sweep backward from the inside running back toward the rear of the car."
Third link:
"Some higher performance cars come with "directional rotors", which have curved or tilted internal cooling vanes. These curved vanes pump more air through the rotors, resulting in improved cooling efficiency. Thus, there is a left and a right rotor. When the directional rotors are properly installed, these internal vanes should lean toward the back of the car - as shown in the diagram on the lower left."
Waiting for Z1 to chime in and explain why their curved vane rotors are apparently supposed to spin opposite to every other curved vane rotor on the market.
That probably wouldn't help as IIRC the stock rotors are straight vane design.