From my experience banner stacking with mercs, unless every person with your banner is being a try-hard it's not really an advantage. And even if every single person with your banner is on top of your scoreboard, that usually means autobalance see's it fit to fill the rest of the team with the abjectly worst and/or low level people on, so the entire bottom of the scoreboard is filled with 0-4 leechers.
I haven't even played cRPG since the death of byz so haven't experience fighting with or against this banner stack, but I'm guessing it's the same.
its' shit now trust me, i was like lol whatever, everyone knows deep down both these clans are noob so they abuse banner system to stack and get easy multiplier, now the game is ruined thanks, this is worse than having russian cheaters, but whatever i dont care because i know they are noob anyway, everyone could do what they do