Well, I think we have established that the 201 vented and 300E rotors are the same thickness.

The part numbers are different so I assume they are different diameters. You both quoted 284 mm for the 300E rotor diameter. I don't have a diameter spec for the 201 vented rotors, but the 201 solid rotors are speced at 262 mm diameter, and I'd be willing to wager that the vented 201 rotors are the same diameter.

Duke