I agree with you, Opera. I was very reluctant to get V4 but, seen the fact that Sidney only comes with P7, I decided to take the risk, and I'm very pleased.

As far as the armpits are concerned, I suggested long ago that it would be better to start from different arm poses. The way the arm is attached to the body is, apart from one joint on the sternum (!) completely done with muscles. It'ss very difficult to model such an area. But when you start from arm down, arm forward, arm upwards, arm sidewards and iarm in front of the body, you can adjust anatomy.
The only thing that changes is finally the location of points in space, so it should also work in animation by setting keys.
In all cases: as, for example, arm upwards and sidewards have their own armpit settings, both should only move to halfway to met the other. And be taken over by that other. This way extreme movement would be limited.