Why does the Information Manual say "C172S - Flaps 10 (Preferred) for Normal Takeoff", when the models before S-model do not have this note?
The Cessna 172S has more power (180hp vs 160hp for 172R) and higher MTOW
(2550lb vs 2400lb for 172R).
This means that folks used to rotating at 55 knots IAS in earlier models would be closer to stall if taking off &quot;clean&quot;.  Another way of doing it would be to add 5 knots and rotate clean at 60 knots.
Vx is also a bit higher in the 172S at 62 knots IAS.
Vy is at 74 knots and Vbg is still at 65 knots, indicating few changes aerodynamicly, just a bit more weight requiring more airspeed to generate adequate lift, or flaps can be added to increase lift coefficient at a lower airspeed.