Being a non-tournament guy, I stuck with single-faction for the time it took to get my brothers into the game. I didnt' want some sort of net-suggested mega team that whould whomp them and get them to hate the game, so I stick with factions. Besides, I suck at macking good teams, so if I pick a faction for the game it limits my choices and makes the whole thing quicker. Plus, I have something to blame if I lose badly ("I played well, it's these crappy Rebel guys that stink.").

I generally like to play pure or almost pure faction armies in Mage Knight. I espescially enjoy trying to put together a faction pure Draconum army.

Yes, they are possible. You need lots of whelps of all types, Level 1 heros, and/or Scalesworn Tharlls, but it's possible. And thanks to 2.0 and domains, the larger army sizes and domains allow draconum armies to become slightly more powerful.

However, the story line doesn't require faction pure - anyone can be working with anyone for all sorts of odd reasons. I just like the idea of all of my figures being from the same faction because an army of draconum is just darn COOL looking. If I'm not playing pure faction, it's because I'm either using one or two figures as a center piece/harasser, and/or that I'm using formations from two different factions

What I think would be cool is having a faction war for mage knight similar to the one wizkids recently held for mech warrior.

I personally try to play faction pure when I can. They can be downright brutal if played right.

I am currently running a map based campaign in which you pick your primary army..in any battle one must have over 50% of total army points be from his primary faction. You can choose from other factions based on alignment aka the Ork army can have some deathspeakers but no Elven Lords. This has been great fun among my group as it helps focus mini collecting for the members who are short on cash. However, when going to a tourny one must bring his best because that's what the others are doing