The wave styled rotor does seem to have less sweept area but I think the idea is to keep the crap from settling into the caliper. Mine is a cast model, although I cannot remember the breed and its too cold to go and have a look at the mo. But it does grip much nicer and does have a nice,sure feel about it. Check out Galfer or Braking wave disks. I replaced the front disk, which had worn out, on the old 92 bike with a Galfer floating wave disk. Much nicer to look at and to stop with. Cant wait for the front disk to wear out on the new bike so I have an excuse to update to a wave style disk.