So last night I played my rogue alt - which just recently hit level 70 and has terrible gear - on my 3v3 arena team. Boy did it suck. We played team after team that had warriors using Deep Thunder, Stormherald, or other various Blacksmithing weapons that seem to be falling from the sky like it's rain in France.
Not to mention the mages, warlocks, and priests with so many hitpoints and so much resilience that I couldn't even come close to killing them before being out of stuns and most cooldowns used.
The thing I learned from last night is that Mutilate sucks for a poorly geared rogue. Survivability is key when you have 4-5k less hitpoints than casters, and not having Preperation for double Vanish/Evasion/Sprint just doesn't cut it.
I'll be respecing back to a x/3/x build as soon as possible.