Bart,

The SP's came out to +/- $450 shipped, so it's a pretty hefty investment. I had heard some concerns about the R1 rotors from a couple of people here (yourself included), and I read some good reviews about the SP's so I decided to jump in. I will also be upgrading the brake lines when I install the rotors, so I won't be able to give you a direct comparison against stock rotors.