I successfully completed UK yesterday on two different teams:

Team 1: Pally, Druid, Shammy, Priest, Lock
Team 2: Warrior, Shamanx3, Lock

All were level 72 when I did it.

You should never be hit by the smashes. I spread my guys out at the end of the bridge leading to the boss, pulled him with my tank almost all the way back to the team, ran through him and turned around to face him, getting his back to my DPSers/healer. I got up DoTs/curses/faerie fire, then solely spammed my DPS and heal keys watching for Smash or Roar. The moment I saw Smash, I strafed left on my tank for a sec or two, then strafed back when I saw the Smash miss me. The moment I saw Roar, I jumped, stopping casting on all my toons. CoH or Chain Heal when my other party member's health dropped significantly.

Despite my best efforts, I missed the Roar and Smash a few times. It hurts, but I still got it done, even with some misses. Wiped once on Team 1, three times on Team 2 before downing him.

You should be able to do it as your levels are quite a bit higher than mine were. Just can't ignore Smash/Roar.

Hope that helps.