Warband isn't an fps. There is no benchmark for the genre because the game is unique. In the ENL we're experimenting with 8vs8 and I'm personally undecided on the subject. 8vs8 certainly has its advantages but although it's important to learn things from successful esports, they shouldn't be dictating the standards for Warband where the comparisons aren't applicable.
I completely agree with this one.
I personally prefer smaller match sizes like 5on5 or 6on6 because I find them more interesting and fun. Besides, it's much easier to organize (and quicker), both in terms of gathering people and commanding during the game. And most importantly, it would be a lot easier to hold together a clan when you have a standard match size of 5-6. I wish the competitive scene of Warband had smaller clans, where all good players are not stacked in a clan, and clans were able to sustain without having a single devoted person organizing all the stuff.
But, yeah, after all it's a personal taste. We shouldn't come up with a decision with someone's preferences. And since there are no solid reasons, I highly doubt if there's a way to come to a conclusion about the match size, satisfying or at least sounding reasonable to everyone. So, for NC '12, I think it would be best for the sake of this tournament to find a fair number, that'll both suit small and large communities without ruining the experience and keep experimenting on the match size (and on other rules as well) in different events like WTFFS.