You talked about disadvantages of lbd and said there is only one downside. I was listing another one. It might be unimportant to you, it probably isn't unimportant to some others.Oh, I couldn't disagree more. If I wanted to be great with a shotgun, then I had to, naturally enough, start using my shotgun. Now, I'm a master shotgunner because I clicked on a perk point for it.
And there are choices involved. There is the choice how much you concentrate on getting good at shotgun or "waste" points on utility perks? Are you the radical starving artist type who prefers shotty master over everything else or the pragmatic shotgunner who looks after his well-being (food, temperature, ability to carry lots of stuff...) too? Do you invest in minimum melee skills for the moments when your ammo runs out?
Even if it is only about shotgunner, your choice is whether you want more headshot damage with your shotty or faster reload or general damage. Do you want more damage out of stealth or is that masterly or not. And there is the choice of going to level a perk first to 3 or 4 or 5 or distributing the points to get a little headshot,faster reload. Do you want to be really good at other weapons too (beside master shotty) or do you concentrate on shotty exclusively.