The last bit about the shoulders I get, I can see why many people would prefer a full bust, I kind of like this for the sole reason that I could wall mount it on a shelf, a bust would take up a lot more space.
The rest of the things you mentioned though varied greatly on the actual suit during filming. So I'm not sure there ever will be a "perfect" representation in that regard. The dome ranged from clear to almost fully black (with even wispy white lines at certain points) the tendons were regularly applied in different positions etc, the paint is debatable. We see many wonderful custom paint apps on Big chap kits and props, but the real thing was probably closer to this, although I do agree that CP's production and paint apps could be much better none the less.
I really don't like the old 1:1 HCG bust, it looks like a brown boss-eyed horse to me and nothing like Gigers beautiful creation. This coolprops head is the closest I've seen, It's beautiful. But hopefully somebody (maybe CP or P1) will make a version as accurate as this, but with more of the shoulders etc incorporated so that people with tastes more like such as yours can be happy also. Win win.