Did the S5's really come with aluminum rotors as opposed to steel in the S4? Is this true?

 

no

S5 rotors are basically the same as S4 ones, with machined recessed (bath tub) surfaces, and they are slightly lighter.

 

higher comp too

 

It'd be cool if it was aluminum.

 

No it wouldn't.
People have this misconception that lighter (rotors) are better.
In reality, the bearings take a major beating with lighter rotors.
Unless you wanna rebuild and swap bearings every few months, lightened rotors really do nothing for you by headaches.



-Ted