I have a complete set of shoulder JCMs now, and one for the elbow bend. On the left the high-poly version with **phantom3D**'s JCMs, on the right the low-poly version with mine. These are first, rough versions and will need more detail work, but you can see how the rubber hose effect is starting to disappear. I discovered that a good technique is to do the morphs in stages. First bend only a little and hammer that into shape, then go to more extreme bends and fix the details.
I think so far my working hypothesis that imitating real shapes and approximating the way the skin would stretch makes for JCMs that combine well is still holding.
-- I'm not mad at you, just Westphalian.