In many rigs I have seen, the root bone is located in the pelvic area. However, where walk cycles are concerned I have also seen tutorials where there is a ground bone (or whatever you want to call it) that is hierarchically above the pelvic bone, but of course physically located at the lowest part of the armature - usually Z:0. This bone serves to position the entire character while walking, jumping, etc. Today I found myself asking: couldn't that just be an Empty instead?
What are some possible advantages or disadvantages of having a ground bone vs using an Empty (as a Parent of the Armature object) to control the character's position?