On my server there is tops 6 people in any of the CoP zones for NA prime, only a hand full of shells actually do ADL, and the JPs are split themselves to Whitegate while NA rule Jeuno.
Six people is too many for a CoP zone unless you’re really lucky and they’re all Beastmasters sticking to EP mobs. In most cases that means there's at least one person doing at least one set of mobs in the cycle of mobs I want to be doing.
Hell, if it’s Tavnazia, even ONE other person in zone and it’s pretty much be guaranteed you’re boned. There’s really only
one good farming cycle there for DCs.
With the exception of one particular mob, my partner and I can clear any of the DC group of mobs we farm all by ourselves; ANY competition can drastically reduce results. For both us
and the other people there. Which leads to serious frustration.
We already can't run on weekends without getting significantly lower numbers than usual because the zones are just too damned crowded.
Before we enter we search all zones to see which is the emptiest. We’ve got a pretty good feel for the people who run consistently the same times that we do. We can almost never do Valkurm (normally 15+ people). Qufim is generally 4-8 people and we have to ask around to be sure no one is doing the mobs we do, otherwise we’re boned. Bubu is the most forgiving, generally there are 5-12 people and there are more options for acceptable targets. Tav we don’t do unless it’s completely empty.
But one random person who doesn’t both to search before entering and who thinks they’re going to farm the same mobs can mess up the whole thing.
A merge would exponentially compound this problem.
As far as merges causing friction, I’ve noticed no serious issues between Seraph and Bismarck players. That said, I still miss being on Seraph.