Definitely looks better.
You'll also need a volume in the neck to represent the internal muscles, otherwise the external ones will have nothing to attach to/collide with, so they'll appear to flop around rather than be part of a functional system.
You'll want one to represent the internal organs in the ribcage/thorax as well. This'll help out with collisions. One thing I've been experimenting with is having the rib cage volume being more dynamic, by attaching it more loosely to the ribs. So that it has some of it's own inertia. In this case, you wouldn't pass on the rigid ribs to the skin simulation. Only the dynamic stuff you simmed in the muscle pass. Just an idea for you there!
Think those back legs could be more refined, yep 🙂