I would not be able to ride such a bike on the road. I prefer sports cars to trucks. The road bike is so much more fun. As to ride quality, a properly designed ti, carbon or steel frame is more than adequate. Then too, with a touring or cyclocross frame you can run wider lower pressure tires: as wide as 38 mm.
I used to ride a touring bike with 38 mm tires long ago. I put new wheels and 25 mm tires on it and it was so much faster and enjoyable to ride. I went from truck to sports car except for the too heavy frame.
One of my older (66) friends who used to race cross country switched from a full suspension ATB to a 29 hard tail. He says the comfort is about as good and has adapted to the slower acceleration. He changed out his 22 ring for a 20 for the climbs. He also uses smaller rings for the mid and large ones.
Comfort is somewhat dependant on how one rides. Off-road you're off the saddle on the rough stuff and I am as well on road.
Al