MTI,

Not all 201's can use the 400E brakes. I know the early 90's 2.6L work OK, and Rik documented that on his website. I don't think they'll fit the 190E-16 and I never seriously looked into any other 201's. They use a different control arm, and/or knuckle/hub, depending on the model. 6mm doesn't sound like much but when that's the total gap between rotor and LCA, it's a big deal when your new rotor is 6mm deeper!

About the 500E brakes. Porsche did some design and assembly. The original brakes were aluminum Brembos, but they made noise when the pads wore past 1/2 way, and due to customer complaints the dealers were swapping them with iron ATE calipers from the SL320 which were functionally equivalent, but heavier. Later 500's were upgraded to larger 320mm brakes from the SL600, those were ATE iron calipers, kinda heavy for their size. But there were no Porsche-specific parts... I think Porsche's brakes are made by Brembo anyway, just with the Porsche logo on them. (?)