I too have recently teamed up with a rogue for 2v2. I was full UA spec and survivability was an issue. Reason is you will be primary target cause rogue will be stealthed. So even before you get a chance to cast UA you could be over run. We came out against a 2 x rogue team and i was dead before i knew what had happened. We still won 4 out of our first 10 matches which wasnt bad for our first attempt.
Anyway I have since re specced 27 / 34 / 0 for a Sl/Sl build. Obviously it has greater advantages with armour and damage bonus.. the only thing i miss atm is the instant howl of terror. Its a spec im still getting used to, but with empowered corruption, Curse of Agony and SL still in my cast bar it should work better.
Also bring out your FelHunter to devour magic + spelllock
hope that helps