I did my research, test road both, and went with a 2016 8.5 DS (upgraded for the better components and remote lockout). A buddy has a FX 7.3 ... on the rail trails we ride, the DS is indeed more comfortable and capable, as steve_cay suggests. I disagree that the DS "does nothing well". Its an excellent dual-purpose bike. I also tested Giant, Cannondale, and Specialized equivalents. For the money, Trek was the winner for me. BTW, my LBS let me borrow a new 8.3 for a few hours to go test on a trail ... certainly that helped me decide.