Please correct me if I am wrong here, but to me it looks like F90 M5 standard brakes are the blue caliper M Sport type. Now, the standard rotors there might be dimpled, or not, can't tell. (BMW offers optional carbon ceramic brakes for M5, I guess for those folks who have money to burn.)
Therefore, I don't see how would standard M5 brakes be better than standard M550i brakes, as they are both the M Sport design, that is, if I am right about M5.
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