When you try the Redirect method (which you should), I would apply it to the whole model, but continue using your existing method for the leaves because it gives each leaf a different direction which is probably more interesting for leaves that are very close together. So for the leaves I would have the existing method followed by a Redirect shader with the overall tree motion. For the trunk, just the Redirect shader with overall tree motion.
Or you can put the Redirect shader after the Parts Shader, so it applies to everything.