A group of players from the same clan as a huge effect on the cohesion of the team, which in turn has a huge effect on the winning chances of a team. Even if there are like 4 Byzantiums on, our easily recognizable banner and us usually picking a direction early ensures many people follow us. Creating a rapetrain not actually consisting out of clannies, but people following the clannies. We make decisions when to fight and when not to fight and the randoms usually follow us in these decisions. If a team consists of only randoms without communication, nobody wants to go in alone, people spread out, run away and then the team loses. This effect oon cohesion that a group with the same banner has, regardless of their individual skill or level, should not be understated.
If you find yourself on the non-stack team you are usually losing because of a lack of cohesion, people running away and not fighting when they should, not because of a disadvantage in skill. Our stack usually fucking sucks these days, but we create cohesion nonetheless and win. This also means that you as a solo player can beat the stack by inspiring cohesion in your team. I have done this myself countless of times, throwing out a a quick 'FOLLOW BAT 1' and then going somewhere usually has half the team following you. Most randoms like cohesion, they just don't know how to achieve it. The group of 12 clannies suddenly doesn't seem so strong when faced by a cohesive group of randoms.
Banner balance can work fine as long as it takes the effect a banner group can have into account. A player part of a banner stack should be regarded as a bigger player by the balancer than he would have been if he were to be judged individually. This creates teams that are always stacked against the banner group, which means that banner groups that are simply stacking will get absolutely wrecked because of a disadvantage in sheer skill and levels. I think the balancer should even do unfair team numbers. Put 40 against 32 players or something. I don't mind, I love a challenge.
For those people that are saying that clans should not be able to play together, fuck off you anti-social bastards. I don't have half the fun playing on my own as I have playing with my buddies on the same team.