I'm still working on the shoulder deformation.
Here's what i've got so far.
I think i'll add a joint for the armpit area and see if can improve the forward arm raise. Also ill fix a helper joint on the back swing movement.
Basically I'm using set driven keys for example the clavicle joints rotation telling the clavicle's translation to be adjusted during certain moves. And today i duplicated the upper arm joint to make a joint that the upper arm can tell how to control the entrance into shoulder. I think by adding another duplicate for the arm pit region may improve the deformation.