This is more of a comment than a question. In a number of Kent's excellent sculpting courses he comments about the strange behavior of the root vertex of the mesh for the skin modifier used to block out a base mesh. The most recent Blender docs explain what the root really is for. The base mesh of the skin modifier can be converted to an armature. The root vertex becomes the root of the armature unless there are multiple adjacent edges to the vertex marked root. In that case an additional virtual vertex is created to serve as the armature root. It is this extra vertex that causes the geometry to shift sometimes when you select a new root. Probably best to leave the root at one end and insert more vertices yourself to have total control.
