BJC,
The TR design is made to meet the needs of the mission/customer. For the S-76, we chose 35 knots of side flight with 10% remaining pedal travel, built a TR that could do that and met that handily. At 10,300 lbs, the S76 can go 51 knots sideways, at 11,700, it can go 35 knots.
For the Black Hawk, the design point was 45 knots sideward at 16,700 lbs at 4000 feet and 95 degrees F (7300' DA). That gives almost 60 knots sideways at sea level (I used to use the Doppler at 105Km/Hr to prove the point!)
The idea is to design each system to do the mission, and try to not use a flight manual caution as a safety device.