I am using the plain-Jane - Michelin Pilot Powers, with a max. rec. press. of 42 PSI for both front and rear. I have been running 36 Front and 42 Rear, as the owners manual recommends. Tire longevity was good, grip seemed good. On other bikes I have owned, I found that running at or near the maximum recommended cold pressure on the tire sidewall would yield maximum tire life. Since the rear was already maxed out, I tried 40 to 42 on the front. Seemed to take less steering input. I never pushed the bike very hard, so I have little feel for where the limit of traction occurs.
Then I read HELLGATE's advice, telling about using pressures around 30 PSI, making a whole different motorcycle. (Now I have seen Hellgate run at the track, and am convinced he knows his stuff). So I tried these pressures & he was entirely correct. The bike seems glued to the road, and was free of the bounciness that was mentioned.
So for best grip, the lower pressures are a big improvement. If you aren't worried about tire life, then go this route. I have seen tires get scalloped due to low pressure, but that is a different subject. And for all around moderate riding, and reasonable tire life, the 36F & 42R is good. Then for maximum tire life, use 38-40 F and 42 R. that's my $ 0.02 worth.