ApexPC:Note - you can only move the grid around on the green if you are in Chip or Pitch shot mode.
Moving just the aim marker is still an essential tool for evaluating the roll of many putts. It allows careful asessment of the undulations.
Loads threads on this but use all the tools available. The differing views (yes chip pitch mode on actually when on a green), then also the aim marker for those ups / downs. You can get a very good minds eye 3D view for putts.