Actually, shrimp like the CB crank out a lot of ammonia for their size, but ammonia is also the easiest waste product to get absorbed via nitrogen cycle.
I also consider the CB to be the best looking of the bunch, but they are the most aggresive. I have one about 3" long that has caught two pretty good size cleaner shrimp just a bit smaller, and ate both. This is with a 55gallon with plenty of rock. He also catches bristle worms on occasion and has shredded the tail on my maroon clown a few times. My CB ignores my hermits, and gets kicked in the face when he messes with my sally lightfoot.
If it weren't for his feelers almost a foot across and security guard like attitude I'd trade him in for a couple of cleaners or fire shrimp in a heartbeat. The cleaners are far more beneficial if you have large fish like angels or butterflies in the same tank. One shop in town has a large CB with a body about 5" across, and he will catch larger fish.