When I played last night (my morning), spawns were pretty constant. About 5 minutes after the 4-6 of us who were there finished one off, more would keep coming.
If you're camping the spawn, you'll see one or more controllers spawn first. About a minute later, you'll see a ton of other things spawn right afterward, then a constant spawn of something for about 10-15 minutes before a slight lull before the next spawn.
And there are a few things that you should bring if you go.
Tamer should bring greater dragons or hiryu. I have a cu, and it isn't getting killed unless I do, but it isn't really shining against the controllers.
Warriors should bring a dismount weapon, a demon slayer weapon and an undead slayer weapon. I've heard that a mystic weapon works well against the controllers, but I haven't been able to successfully test it.
Mages should bring an array of spellbook and a tamer to stand behind. You can't cast energy vortexes in town (but you can at the dock), which means that bringing the fight to the bad guys is pretty difficult.
The most successful people there, as far as I've seen, have been the archers and the tamers. If melee fighters don't work in groups, they get eaten alive rather quickly.
EDIT:
I forgot to mention. If anyone there sees Farsight (following a cu into battle) or Kei Wa (A mage hiding behind someone else's tamer), I will be MORE than happy to help anyone out in getting a new horse, however I can. I want to see a whole lot of these things out there, and I'm not a good enough tamer to get one on my own (110 taming, it would take me about a million tries, from what I've heard).