They made improvements to reduce the heat on the sprints in '06-'07, I think. I put 20k on the FZ6 and 12k so far on the Sprint, all in hot, humid gulf coast weather & even hotter central texas summer touring. At speed on the open road, the 2 bikes are about the same: I feel some heat through the mesh pants on the "downwind" side of the bike, but it hasn't been a problem with either.
My daily commute is about half 70+mph freeway and the balance redlight little towns with plenty of traffic (adds up to a 30mph average). The only time I notice the heat is when stopped in traffic for a while, and the thermostat kicks the aux fan on. That puts more heat on your legs, but otherwise I have never had a problem. As soon as you are over a walking pace, you don't feel it. I don't think I have ever kicked in the aux fan when moving, and I did some very hot touring rides this summer. I wonder if that is what the others were reporting on the demo day?
I have heard people complain of heat through the seat on long trips with the underseat exhaust, particularly for the passenger. I have never noticed any heat from the saddle as the pilot, even on mid-summer 300-400 mile days. I never ride with a passenger, though, either.
Hope that helps.
