I think the Agea Karan looks better imo. And yeah I wish the hackdirt thing was a bit more fleshed out, I mean you can avoid ever seeing the brethren during the quest. I think there are a few mods that touch on the quest but nothing really giving alot of background or plot.
If they showed up in OOO that would be awesome,I'm really looking forward to the next release.
Yes, I think Agea Karan looks best so far. It should preferably be retextured to be darker, though. I noticed that glow maps still show through their Darkness shrouding, which could be used for cool effects as well. Whatever comes of it, it won't be included in OOO, but a separate add-on if anything. Probably requiring OOO, though, as it's an excellent base for making bosses.
EDIT:
And for armor ageha tortured soul might be what you have in mind.
I tried Ageha Mage again and now I think it looks more or less perfect: http://www.bluemelon.com/photo/18688/1213855.jpg, http://www.bluemelon.com/photo/18688/1213856.jpg.
I've also spawned/fought them - and they look very cool, they're using the Darkness spell as a buff and Nico's swords look very cool when they're shrouded as you only see the shinyness - so basically a blackness with two glowing eyes and shining sword edges. But it felt a bit same old at the same time - they should rather use some awesome spells IMO.