As I understand it, a big change was made in '93 to directional rotors. The '92s did indeed have aluminum calipers, but since they were problematic the dealer retrofitted calipers from the 500SL.
As I further understand, the brakes did indeed grow about an inch in diameter for the '94 model year. I personally have the 500SL binders and they work fabulously; doubt if I'll ever do an upgrade beyond perhaps drilled Brembo rotors.
Best regards, Michael