Stone Melee + Dark Armor means that you can combine Fault and Oppressive Gloom to create a Mag 4 PBAoE stun that can be kept up as permanently as you like, leaving everything short of Elite Bosses stumbling around like fools, and you have lots of reliable knockdown to round it out. That alone provides phenomenal survivability in PvE; add in the full-heal in Dark Regen, respectable resists across the board, and impressive exotic protection, and you should stay very healthy against any enemies that you can bunch up and stop from sniping you in a spread-out room. The downside is that relying on heavy-duty stuns and knockdown can hurt your fury generation (which is why I prefer the combo on a tank to a brute), and large crowds that prefer to stay at range can still pack a world of hurt.
Regarding the psi proc in CoF... damage procs in any damage aura tend to be somewhat lackluster. They have a 20% chance of activating every 10 seconds after you activated the power, whether or not there are any foes in range to hit, so you're looking at less than 2 extra damage per second to everything around you over an extended battle. My Ice/Storm controller relied largely on stacking damage procs in his various debuffs, but he could layer on a dozen of them, so it pushed his kill speed from downright glacial to fairly tolerable. If random bursty damage is your thing, you can do it, but I wouldn't expect much from Cloak of Fear, with or without a proc.
Rule number six of an empathy defender is NEVER underestimate a blaster's ability to die. I don't care if he has CM, Fort, both RAs, bubbles (both FF and Sonic), and is fighting next to a Storm defender with hurricane on. If there is a way to die in that situation, the blaster will find it.
I know I will get some snickers, but I wanted to try out a a stone/dark brute. I really just wanted to know about the effectiveness of OP and stone stuns pve/pvp & how good the psi proc in CoF is. If anyone has experience with it or numbers I would appreciate that feedback.
Thanks!