I personally think this whole business of flying on the step is a load of c**p.
What decides a final cruise TAS is an equilibrium between thrust and drag, remember, excess thrust can either make an aircraft accelerate or climb, once the total thrust is equaled by the total drag you will have level, unaccelerated flight.
I can appreciate that climbing above and then diving down will seem to yeild a higher speed or the same speed in less time than a normal level off and acceleration, but unless the two methods can be made under the exact same thrust / weight / ambient conditions any conclusion that is derived is purely subjective.
If anyone can post scientific data derived from proper flight testing that shows existence of the mythical "Step" I would be very intersted.