I've been riding on Grand Bois Cerfs for the past few weeks and the ride quality is incredible! I'm a little slower than when I was on 23s (Continental SuperSport Plus), but the ride is so plush and still feels quick, that I don't notice I haven't been hitting my previous top speeds until I check Strava after the ride (my average speeds though, which I count as more important, have gone up). Only have ~200 miles on them so far, so can't personally speak to the flat protection, but I've had buddies ride on them till they've worn out without a puncture.