interesting…my turbo bike is TCR running 25mm tyres, so i have gone up a mm with the SL7 but with the Rapides being built around the 26mm tyre, I have spoke to Roval they say for speed and aero stick with 26mm but for that bit of comfort go up to 28s.
I am curious about trying the 28s for sure, my mate has the same set up as you 28s GP5000 SL6, he enjoys them. I just wish GP5000 had the tan wall, instead of that limited edition set that only come in 25s boooo.