I weigh 230 lbs and run 80 on my 32mm 700cc tires. I've played around between 90 - 70, after many years at 90. I honestly couldn't tell much difference but flats did go down at 80 compared to 90. The science says lower is just as efficient if not more and pinch flats did not start to happen at 70. If I lose weight, I will lower it.

Earlier this year I did the Seattle to Portland ride on a rental Fuji road bike with 32mm tires. I forgot to check the air pressure on the first day, felt fine. On the second morning I checked - the tires were at 65 psi! I pumped them up to my usual 80 - psychologically, I felt faster. Looking at numbers - no difference.