Two years ago I jumped on Niner RLT9 Ultegra build that I found on clearance. There’s nothing radically different from the drivetrain of my road bike, actually less range at the extremes. 11-32 cassette and CX style 46-36 crankset versus an 11-32 and 50-34 compact on my road bike. It also came with 35C Schwalbe G-ONE tires. They roll very well on the road and are plenty good for the gravel roads around me.
I took it out for a maiden voyage on very familiar route, 30 miles round trip, all paved. I honestly felt slow that whole ride, somewhat demoralizing. Once I started reviewing the data however it turned out to be my best time ever on that route. I think it was just the fatter tires running at lower pressure blunts a lot of the road vibration and I perceived that as feeling slower, when in truth I was moving along an average 1/2mph faster over the entire ride.
Since then I’ve come to appreciate it more and more and it’s pretty much become my go to bike now. It’s certainly more stable, comfortable, and my fitness level it’s been consistently faster than my road bike.
That being said, this is all experience from a rider that has never done any structured training until very recently, figure I was in the 2.2W/kg range. I suspect my perceptions will change as my fitness improves and I’ll begin to find my dedicated road bike has an advantage as I get fitter and faster. I don’t know if it will sway me one way or the other, but I look forward to figuring it out.