Since your wanting to improve your calves, i would suggest keeping your feet on the ground but make sure that at the top of the movement your right up on your toes (as if you were doing standing calf raises) so you get a full contraction of the calves, and at this point you should also have a peak contraction in your traps. This way your able to hold the full contraction of both calves and traps at the top without any impact from landing. Other than always keeping your toes on the floor, i'd do the movement as they show (using a little quad power to handle a little extra weight, but under control). Hope this helps.