Alberto Pires, a bike journalist from Motociclismo Portugal, had the opportunity to ride the RSV4 of Max biaggi. You can see one of the rounds in the video.
He also rode the BMW SBK and this is his experience:
Aprilia dash board is easy to read than BMW ( near to impossible) but we don't have time to look at, even at 20 seconds slower than the Biaggi lap time. There are to many thing's to think bout. First it's forbidden to crash, and that kind of bikes are completely different from stock bikes. Tires are very soft, the front dives to the corner fast, brakes are really powerful and the gear is “racing”, first up. You have to deal with all these differences in “only” 4 lap's, and the next bike is different and you have to start almost from the beginning. Regarding the Aprilia and BMW, the Aprilia is more stiff and more precise. The engine is much more powerfull at middle regime. Riding position of Aprilia is more hard to hands on braking. Aprilia is more stable. The only problem was the clutch lever was not well fitted and shift down was very difficult. BMW is more easy to move but at same time, moves to much on fast corners. Aprilia and BMW Teams have the same level of professionalism.