I manage it on my rogue/hunter easily enough - I'm not sure how you kill the tentacles as certain classes though, I can only hit them with fan of knives/pet while they've picked me up - This was in full pvp gear 550 ilvl. As long as u kill the tentacles before anything else on the last phase and don't lose too much sanity, you should be golden. Pretty much every class can out heal the low damage. The tentacles are the ones that stun you/slow you etc, if you kill them first you won't have to deal with any of that - They also put a debuff on you that reduces all damage you deal by 20%, i believe it can stack.
Also, spine of deathwing isn't that bad at all now - The way you do it is just constantly move left and right while you wait for the adds to spawn. Do it like you normally would, kill 3 tentacles at the start, roll them off, kill the last tentacle and just keep him there. Keep moving from the left to right so that the boss never fully rolls but just constantly changes his mind (tentacles can never stun you solo now too), if you can do that while picking up the slimes then this fight is a cake-walk seriously.