sorry to bring this back to life but, I have the same bike and am having the same issue with the brakes. Fading towards the later laps of the session. New pads and fluid. Power bled, stock lines. Did you find a fluid that helped?
Last time out I had pretty good luck with Endless RF650... It needs to be fairly fresh though. I just keep a bottle with me at all times and bleed the brakes as soon as the lever starts to feel spongy at all, then the lever stays firm the rest of the day/weekend. (I haven't been back to Road America though) Sidenote: If you ever find yourself in the grass, don't expect the ABS to keep you up if you just mash the rear brake. The good folks at Bosch haven't fine tuned the system quite well enough to handle that yet. Ask me how I know.
Ill give it a try. As far as back brakes go, make sure to pump the pedal up next time you re-install the wheel before you get on track. Its a bit disconcerting to feel the pedal go all the way down at the end of the first straight of the day. Oddly, I seem to do this every time I swap tires.