I broke my right shoulder 2 years before I started jumping snapped the ball clean in two. Although I did not need a pin, my movement is restricted to less than 90%.
I used to get alot of pain in my shoulder when I first started and one time my position was so poor at deployment I flipped over and dumped on my back (not good).
When it came to buying a rig I spoke to the guy I was buying from and told him my problems. Basically he said similar things to what this forum has said, I.E BOC tends to be much safer than LEG. But what he did do is have me try on different sizes and types of rigs.
I was very suprised at the difference a well fitting rig can have and have never had any pain or problems deploying BOC on my own rig.
So my advice is try on different rigs when you come to buy, or better still have one made to measure for your bulging dimensions!! It does make a difference.
One thing though, I wouldent buy a leg deployment without at least trying it... you could also have some other rock on your frame hindering leg deployment