Generally I think the suggestion is okay, and clans should be enabled to play together, that's perfectly fine for me. The only problem is: the rest of the server shouldn't suffer from it. What do I mean? That the banner balanced code has its flaws:
Banner balance need 2 functions:
1st: different clans are put into different teams. Not 2 big clans with 10 to 20 players each into ONE team, like the day before yesterday with Shogunate and DRZ. This sucks.
2nd: unless the other team also has got three players of one clan there is following equation: 3 players of one clan = 4 players in enemy team. So the clan teams have to fight bigger random teams. This is fairer for the independant players, and more of a challenge for the clan players.
If those functions don't get implemented, I am AGAINST the suggestion. If banner balance will be improved, I am totally FOR it.
Edit: if you look at the second screenshot it looks like my second suggestion is already implemented. Or is this simple "luck"?