#6 or even 7-1/2 bird shot is just perfect for 3-4 pound pheasants. Hit 'em in the back flying away at about 20 yards and it will knock them down, but won't tear up the breast meat. About half the time you still have to break their neck.
I have had a pheasant fly straight at me, and at about 7 -10 yards, it pretty much fell apart in midair.
Excellent on 3-4 pound birds.
For 200 pound bad guys? Better than nothing, but very limited range. Just not betting my life on it.
For what the guy in the gunblast vid is talking about... bad guy in the hallway and a concern of overpenetration... I can see his point, but again, it's not for me.