You seem to be looking for a response. Not having used that particular servo, I can't add much. However, if you have others that are the same model and this one is different, you should look into that. Different types of servos make different amounts of noise. I can't say any of mine strike me as being loud. Different gear sets will sound slightly different, and depending on how a servo is mounted it can make more or less noise.

If you've only got one, buy another to compare it with. They're cheap little things, so that'd cost you $10. If you really think there's something wrong with it, call Horizon. It's probably not worth sending something so inexpensive in to have it looked at. At any rate, never use equipment you're uncomfortable with on your planes. Cheap servos have their appeal, but if you're uncomfortable with it you really haven't saved yourself anything. Stick it on the throttle, and put something you trust on the control surfaces.