Upper body animations while moving?

Has anyone had any luck on getting smooth upper body animations on a humanoid while moving? For example running and swinging a melee weapon or running and reloading a gun?

I can get an upper body animation to play while moving but the problem is the avatar mask treats all of the spine bones as a single torso mask. So, as soon as you start playing the animation while moving the upper body starts wobbling because it's no longer counter animating the rotation of the hips/root.

A feature that seems to be missing ( or that I can't find ). Is to be able to create a layered animation and then control weight values of each spine bone to blend the spine motion of running and w/e upper body anim you need. The feature is mostly there but the masking setup doesn't have enough detail.

 

I'm not wholly adept at the system but within the animator you have access to animation layers where you can use an avatar mask to define affected areas and you can switch between having th animations override the layers below it or have the animation additive. You can also modify the weight of the layers here.

I dont know if youve looked into this, but hopefully it can help you out.

 

This may be a reason to consider using generic as your rig type instead of humanoid. My understanding is that it allows for much more precise masking.