I really enjoyed the Retx4 and 1 Prot, until they changed Kings in a patch maybe 2 months ago? It was much strongers since you could cast 3 of them, I was able to have 4 sets of kings on my tank, and 2 on each Ret. This was a massive absorb that took out all of the dot damage or random splash damage and made the grind much smoother.
What is your Ilvl? I also ran into an issue where I couldn't seem to get the Ret DPS up high enough to my liking.