I still see 5 man volks getting wiped quite regular by mines because of pathfinding/how models clump, hell I just had a game where the squad was spread out across a road and 1 mine still somehow wiped all 5. - yet vs rifles/cons I very rarely see more than 2 get wiped with a Okw mine.
Do different squads have slightly different movement/"formation" patterns? or does the OKW mine have less AoE or am I just super unlucky?
I think you're just unlucky. I lose a full squad to OKW mines once every couple of games. It's frustrating as hell and that aoe should be reduced. I don't mind the bunch up wipes (that's on me) but if I've got my squad fully spread out it shouldn't die to one mine.