I have the same tank and a onespot rabbit, which I have had since September. However, he is getting too prosperous, too fast. He's eaten all my problem algae (caulerpa) and while he is calm and at home, he's grown, and gotten fat as a pig, and is intimidating to smaller fish, who won't come out except at feeding time. Mr Rabbit is going to have to go back to the lfs soon, though I'm sure that darn caulerpa will pop out the moment he's gone. His max size, however, is 9-10 inches, and the vision of that is daunting.
To my observation, he eats macro algae and shrimp, and has no interest in film algae. I doubt he would eat hair algae. His thing is the leafy stuff like caulerpa. And no shrimp would survive in the tank with him, I fear.