A 70-200 is an easier load than a 24-70/2.8, for example, because it is well balanced (by virtue of the lens collar and foot). Even your 105/2.8, depending on which model, could be a tough load for a ball head because it is so nose heavy.
An M10 is only about $50 more, and a few ounces.
Each progressively larger head can handle difficult loads progressively better when used in "the sweet spot". It has little to do with the payload rating per se, except to the extent that bigger payload ratings generally mean it will handle these difficult loads better.