Chris,
I say no way it will warp
1) The cooling won't be that incredibly rapid
2) bridging between rotor surfaces with conduct heat to even out the temp difference
3) try to drive the air into the internal veins
I just did this myself.
http://www.pelicanparts.com/ultimate/Forum3/HTML/012020.html
Haven't tested yet. I will be taking it to streets of willow next weekend for the first track outing with the ducts. If I can find someone with an IR thermometer I will take some measurements.