JimL - that might be true if the remaining 2 engines could put all their remaining power through the MRGB to drive the rotors and it is my belief that the Merlin cannot do this. One of the good things that Westlands designed was the conformal, 3 pinion gearbox on the Lynx which allowed all the power from the remaining engine to drive the rotor following a power failure. Who built the gearbox for the 101? not Westlands - it was Augusta using conventional design. No doubt a variation on the 3 pinion MRGB would be offered as a mid-life update for the Merlin.
However, I agree that 400 feet is a little excessive - all that is required is enough nose down to achieve about 30 kts and it should fly away on 2 engines. But if your twin engine performance is that good, why do you need a third engine?