The Nimrod was considerably slower - 0.76 Mn in the cruise
Try 0.69TMn The AMT horn operated at .765-.775.
Below 143,000lbs we were cleared to 200 feet on two and had the ability to climb at 100 ft/min on one - sporty.
Critical Weight was not a fixed value and had to be calculated, similarly the minimum height for 2+2 decreased until Crit. Wt. was reached.
Just checked my log books and find a small but significant number of trips 10hrs+.
YS