One of the most tedious parts of painting weight is splitting weight among multiple influences. But with this technique you can easily adjust the falloff between the influences while keeping the same overall weight.
I tried getting this to work with a python callback so that it split as you updated the weights but it was too slow. That's not an issue if you use ngSkinTools but is an issue for non-skinCluster deformers.
I am working a custom node that can split the weights while you paint them but it's a tough task because of the callbacks that you need to have for the animCurves, but hopefully it'll be fast enough.