Also, it's worth nothing that from a vertical perspective, it's not really that the grass is absorbing impact so much as that the grass surface is not allowing the bubble of air underneath the helicopter to escape so readily. So it's an air cushion effect rather than a surface cushion effect. Indeed, leaving aside the air cushion, given the same vertical speed at impact a soft surface will keep the skids from spaying more so than on pavement, and this will transmit a higher shock load to the airframe.
You may have some valid arguments about using tarmac instead of grass aa777888, but that one is complete fiction. search back for Nick Lappos' destruction of the 'bubble of air' theory of ground effect.
Keep straight, don't chase the attitude with cyclic and don't lower the lever until you have stopped during the run on and it doesn't matter what surface or pretty much what speed you land on.