Shoulder holsters certainly have thier places, however it's been my experience that they are niche holsters; usually for over clothing or under clothing. In warmer climates they don't work so well (I don't know how Sonny Crockett did it without suffering heat stroke). I gave my last one away a few years ago and haven't replaced it.
"Don't pick a fight with an old man. If he's too old to fight, he'll just kill you."