I generally think these clans are utterly bad ideas.
These things are essentially what power faction servers, are they not? I may be a member of DIFA, but I generally am one who seeks homeostasis. Sure, in-game I can get to be kinda weird, but I generally will steer things back to where it began.
Now, concerning these clans;
I'm all for team work and group efforts, even PvP teaming. Even so, I can remember a long time ago that there was a super-clan; it contained about 20 people (?) and, as a collective, created so much grief, such as;
"DIFA sucks!"
"OMG DIFA Scams!"
... and then later...
"WTF I got robbed/griefed!"
The last part was mainly caused by the fact that the super-sized clan were all on a huge WG and, because of that, everyone could literally do as they pleased (until they are log-blocked, that is.)
Then there's PvP teaming. I generally believe that "If you die in PvP, your items are at the mercy of your killer." But then, there is the following situation:
Player in good armor walks in. Beats a few heads.
Other players who have nothing to lose run in and punch him/her, locking the player in PvP.
Eventually, (I mean this is spades) the player dies/loses his/her equipment to endless waves of fisters.
Now, as I said before, "If you die in PvP, your items are at the mercy of your killer." I elaborate and say that this applies in a fair fight. I hardly see losing your hard-earned gear to people who go in with nothing just to chip away at your armor as fair.
tl;dr
I'm sick of these new clans popping-up (at least the ones that do nothing but clog the server chat with drama).