What is Full-Floating?Full floating rotors, such as were originally conceived, were designed to reduce the tendency towards thermal stress induced distortion due to uneven thermal expansion under load. Prior to the introduction (by Brembo) of this design, brake rotors in the motorcycle industry were simply round discs bolted solidly to the wheel. You may remember if you've been around long enough, the rotors on the early CB750 and Z-1's were nearly 7mm thick and weighed accordingly. This was in effort to keep them from warping. Now days, the only road bikes coming through with solid mount (front) brakes are the Cruisers and budget bikes.
Today's Sportbikes abound with trick features and hardware in every nook and cranny. Brakes too. The brake rotors on them work remarkably well considering their mass-produced (read: stamped) manufacturing process. These are technically semi-floaters as the outer SS blade is nearly bolted solid to the carrier via the stamped stainless steel rivets.
True full-floaters move on the carriers, this allows them to self-center in the caliper for reduced brake drag and "float" unimpeded for unrestricted expansion and contraction during repeated thermal cycling. The only serious down side is a bit of rattle that reminds you these are indeed full-floaters.
Does all this guarantee they won't distort under severe duty conditions? No, unfortunately, there's precious few guarantee's these days. But they do perform as advertised in improving overall braking performance while significantly reducing that distortion tendency.
BTW: All Superbikes, GP machines and the like unanimously have full-floating brake rotors