Is it something to do with how much airspeed through the disk you need to get translational lift perhaps?
Seaking "burble" comes pretty quick, therefore not so much nose down and subsequent height loss required.
Perhaps other aircraft require more vigourous acceleration to get the benefits of translational lift due to relative rotor size?
That being said, we used to practise single engine failures next to Rinsey Cliff (approx 200ft) in the SK 5 by lowering the lever rapidly to single engine power, and you needed a lot more than 5 nose down to get going.