I only have 1 ride in on my Gravel bike... but I'll just grab a 5 mile segment from strava.. Granted the bikes are different but nearly the same (except for the gravel bike being 2lbs heavier, but same powermeter) This 5 mile segment is flat and just riding.. not pushing because it's a MUP on the way to Mt Diablo.

TurboCotton : Avgspd 15.9 Pwr 157
G-one :Avgspd 14.1 Pwr 167

Far from scientific I know... but hey I can feel the Crr :)

Here's another 3mi segment.

TC Avg 18.4mph Pwr 170
G-One 17.0 Pwr 198

I mean there are a ton of other factors I'm sure... but no doubt in my mind the 30c are slower by a good margin and yes they are the "speed" model. I'm selling my #1 road bike and this one will have to do until I buy a new fangled "aero" bike... fast group rides are going to be harder unless I swap the TC back on.

all in all the whole ride took about the same time... but I avg 24w more :) It will make me stronger