Interesting, the sweep area is greatly reduced, so I don't think I would use those on a road course. I guess they would be fine for daily driving or drag racing.
I am losing about 6 lbs, but gaining about an inch and a half of sweep area on each front rotor by using larger 2 piece rotors on my car. 25-35 lbs with significantly less sweep area doesn't seem like a good trade.
I do like the way they look and some bikes use rotors like those, so I guess we will see what the reviews are like.