In my experience most marines have pretty much the same load out 90% of the time they play. When did you roll with B8 M44 heavy last time? What about a kitted out smartpistol? Slug shotty with accuracy attachments? What about big range OT clay?
When I tell people even in game to try out totally different guns with totally different attachment that they think are worthless or pointless, they are really surprised how much you can specialize killing things.
Again I am biased as I am playing the game differently. I never play as a Swiss army knife do it all. I'm a minmaxed glass cannon 90% of time. That means 90% of enemies will kill me easily and I cold not possibly kill them....well I avoid those 90% of enemies. if you read my replies you know how. For the rest 10% I am a nightmare to deal with as my sole job is to kill them. Be it an OT with my 50 claymores (read my other post that I am not exaggerating I actually deploy with 50) or do some other think that DOES look retarded....but it works perfectly for that 10% of things.
Again that's just how I play so you won't experience the things I do because you are not minmaxing. If I decide to make a hydro FOB, I will do it. When did you take 15 C4s and 400 metals as an engi last time? Well I that to totally achieve what I'm doing. What ever I have in my mind, I will go all out breaking all in-game, SOP or meta rules just to do it.
So back to runners...meh. If I'm kitted out to hunt them..read carefully..THEY WONT JUMP OVER MY CLAYMORE. They can not run in full speed because I place them in chain to a place where they will pounce. I'm not sure why I need to explain how to abuse the game. It's not supposed to be. You are supposed to think runners are OP. Well...they are not.
As for BOO and the rest. Played a lot with them. For ever boo you got 10 XX. Really unlikely to run into actual good players.