Given his healer would be the 4th paladin, I can only assume you want the feral. My only experience with him on his healer was a very successful H AN run, so he does know where his FoL button is.
I've grouped with his druid on several heroics and vault raids. I met and was impressed by him before I knew he was an alt of one of the guys in my raid (before he joined the guild; he joined shortly before ya'll did). In Vault10, Arlden actually pulled aggro off of Troa early on- which I consider very impressive. He's always situationally aware and moves with me for Kologarm, etc.
Coreus in general is an intelligent and faithful raider, and none of his alts I've met so far are exceptions. He's an Aussie and a Whiskey sub, so make sure that your raid time will not put undue stress on him before comitting.