I know the topic was pedals. But I got a steal on a new-take-off R9100 crank, and the ramping and weight on that thing is stellar compared to my old 105 5800 crank I had. Like light years better. I went ahead and got R8000 FD, RD, and cassette also. I can feel some of the shift magic of R8000 that way, but miss out on the shifters. The most expensive and toughest parts to change over. But, still super satisfied.
I have the 105 or RS500 version of pedals from 3 or 4 years ago. They still feel fine. A few grams. I run speedplays on the TT bike for the aero and reduction in stack.