I had my 225/45/17 Michelin Pilot Sports up at 42/40 PSI. Over 50K miles, I noticed the middle of the tires were wearing out faster than the shoulders. Over the last 15K miles, I've decreased the pressure to 34/30 PSI and noticed no decrease at all to fuel economy (still getting 45MPG), better braking, traction, less tire squeal, and no more oversteer when taking turns like crazy.
When I had my stock 195/65/15 Michelin Energies, they seemed more sensitive to pressure change. I say this because I noticed a 2MPG gain when I upped the pressure from 30 to 44PSI. This leads me to believe that every tire compound and design will yield different results.
After 65K miles on my Pilot Sports (great tire btw), I'm going to try out the Pilot Sport PS2s. Best review from Consumer Reports and seem to have good reviews from users on tirerack.com. I'll note any fuel economy vs PSI differences.