My latest 2 teams include a hunter - why - automatic off tank. I also have 2 droods and 2 shammys in my current team - why - flexibility.

I define hunter pet attack as one of my CC spells. (I also have to druids with entangle). I can then allocate a 3rd "CC" target and when I hit my CC button, the pet starts off tanking a mob while the droods entangle.

Makes multi pulls much easier.

For easier kills, I transfer my tanking druid to my DPS group (have that on a button) and let him cast. I also run with healers set to zero most of the time, and just burn everything down, but should things start going downhill, I have still have the option to transfer up to 3 toons to my heals group (main healer is drood, with 2 shammys as backup) I frequently switch leaders at this point and let the hunter take point. His pet can tank, and he can take more hits than a clothy if things go pear shaped.

In answer to the question, I thank I'l always take one hunter, but not sure about more than 1 (healing would concern me, but I'm a cautious player)