I just ordered the TS1 driver after getting fitted by the Titleist rep at my local course. Fundamentally it averaged 12 yards more carry (212 yds carry, 15 yd rollout) with the same rollout as my current TS2 . I am a senior with average head SS of 83mph and 12 hcp. I will be selling the TS2 I bought 6 months ago,,,which is rather painful. Prior to the TS2 I used a Callaway Fusion (2014 I recall) for years happily but the roll-out was rather low due to higher back spin probably. Additionally, a deciding factor for me is that I find my longer clubs, especially the driver, are more difficult to swing later in the round as fatigue sets in. I'm hopeful the lighter weight (lower MOI maybe) will lower my urge to swing harder to keep the speed up. BTW, I am an retired mechanical engineer and understand kinematics, dynamics, and MOI better than the average bear. Unfortunately understanding things in your head does not translate to playing good golf in my experience.