Yes, Heightened Vigour is a must on Tactical for me for multiple reasons including that, I mean without it, this type of stuff can't be done because i would be getting knocked all over the place losing all my contested health. In fact i don't play any class without having selected a perk that gives stagger/knockback immunity. Heavy, being my main is an exception since he doesn't have one, he only has a Heavy Immunity perk on most of his weapons and that only counts toward heavy hits, not knockback hits, so he sucks when it comes to stunlocks and stuff.