First, I would like to say, great review... organised, well-written, and thorough.
My thoughts on the motorcycles
CBR 600RR: Overweight, Overpriced.
GSX-R 600: Yesterdays technology, but still a close competitor
R6: It's neck and neck with the ZX-6R. With different tires or a suspension setup, it might even be faster.
ZX-6R: The best of the best. THE bike to beat. How can you argue with radial brakes, inverted forks, and the lightest weight of the bunch. A little extra power always helps, as does the price tag of $8,000.
Expect Honda/Yamaha/Suzuki to hop on the bandwagon, and build future 650cc sportbikes.