*I dont agree with you , for exemple , i get a ilvl 637 feral drood with nice gear (almost 29% crit and 5% multistrick) without any buff and i can tell you that in full buff with pre pot and flask i can reach the 55-60k dps on pull and 21-25k dps at end , I find the feral (if for sure he is really well played) one of the best dps class.
I agree with you on one point , when we get a fight with aoe dmg we are f***ing useless , but with 2 target we can be good.
To answer to your question "Shackle" , dont take the 30% savage roar , refresh this spell arent realy hard
Moreover , play with FB most of the time and when you get a fight with 2 or 3 big target , (like a council or Twins) take moonfire skill.