Jeez this thread is dead! Where is everybody? (Hope I didn't scare everybody away ;-)
Well I guess I'll answer my own question! I got some Orion B tyres and the black and blue inserts finally, and tried them out on the weekend.
They weren't too dissimiliar to the Takeoff 27s that I have been using in terms of handling. If anything the tyres with the blue inserts gave slightly more turn in and the black inserts gave slightly less turn in.
We ran about 5 runs on each set and a couple of the tyres were almost worn through to the canvass in spots, but the performance didn't deteriorate.
I found slightly heavier damping helped maintain the corner speed that the Takeoffs had but other than that I didn't change the setup much.