Fear is a bitch and a shaman for the fifth wouldn't be a bad idea. Honestly I'm not sure what the best fifth player is. I decided to roll with a fifth priest using the logic that if I could, I'd have 25 priests all spamming holy nova (assuming it hit raid wide, and not party), so why not maximize the synergy and go with all priests? However, I think a shaman would be good for protection against fear, a mage for frost nova (combined with fear would be nice so they stay in the AoE storm), or a DK for those damn hunters that continue to rape me.

I'm certainly not the best player around, but I'm having trouble with dispell rotations when I have only one guy fear warded. It's probably because my system isn't set up for quick enough reaction. However, even if you just use the simple method of every priest has a fear ward and every priest has a trinket, then you're still getting two fear protections every couple of minutes - better than my druids at least.