Originally Posted by JAJ
I never found any information about why the rotors have different part numbers. In my case it didn't matter - my Canadian 2008 E92 M3 came from the factory with the correct rotor part numbers to use the Sport pads. I just wasn't willing to pay $1600 for a set, so that was that.
While these prices aren't final, I've found them for around $800 for a set. I should know more by tomorrow.