Survivability in defense gear as fury...sure you can do it. Your threat is gonna be bunk however. Without the crit to keep flurry up, you'll hit like a wet noodle.
....either way, I usually inadvertantly end up tanking half the heroics I do as dps these days anyway...in my normal dps gear. Stuff dies fast enough it doesn't matter it seems. I remember when getting hit for 7k was unhealable....now hots and ae heals can keep me up as I'm "tanking" trash. A week ago I tanked a random heroic UP in my dps gear as fury in zerker stance, the whole thing, every boss. Healer (semi-geared paladin0 never dropped below 20k mana. I mean for crying out loud plate dps gear has soo much stamina on it I sit at 31k+ health self buffed in my dps gear. I've come across some random tanks in heroics that have 23-25k.
...I even jokingly tried to make things interesting for him by popping recklessness and DW at the same time on phase 2 of the final boss. He never let me drop below half my health and the boss died before the first smash.