I might have a link to the original study buried deep in my email. I will have to check. I have a friend who is a total economist statistical nerd (and I mean no disrespect by that), and he swears by BQ's tire study results. He sent me one or two articles a few years back.

I switched from 23 to 25 on my Madone early last year (I think it was early last year). I noticed no difference in comfort or speed. Also noticed no difference in comfort when I dropped the psi from 100 to 90. I did seem to ride a bit more slowly at 90 so I went back to 100.

By way of disclaimer, most of the roads I ride on are in decent shape, and there's not much chipseal.

During the brief period when I had the Bontrager TLR wheels on my bike with my 25 mm Gatorskins, the discomfort level was huge. In that case, dropping the tire pressure helped but did not solve the problem. Switching to different wheels solved the problem.