Long time Gator rider .... but thought I would try the GP 5000's.
I ride the same route, (just longer or shorter). I know every bump, depression, utility cover and gouge in an otherwise smooth surface and thought the route would be easy enough on the GP 5000's. My route is along the coast and is due north then due south, so wind is equally in my face and at my back during the ride and it is flat.
My normal ride is 16 miles and takes 60 minutes +/- 1:15 (15.8 mph to 16.2 mph). Obviously, some human variability here and was :58 flat yesterday on Gatorskins (16.6 mph). This normal speed/time/distance estimates watts at 120 - 130 to the road, over the hour. (so weak)
Anyway, riding today on the GP 5000's with similar effort as measured by HR and perceived effort, (no power meter), time was 55:50 and avg of 17.2 mph. Using rolling resistance calculator, I should have picked up 18 to 20 watts (+/-9 x 2) for Gators v GP 5000's and that is exactly the speed I picked up. Speed/time/distance estimates 148 watts to the road, at 17.2 mph. The GP 5000's are stealing less watts due to lower rr.
So, will wait to see on durability, but the pickup in speed due to lower rr is for real.