This site talks about feather loss in general. I don't know if it will help you or not.
Kansas State feather loss
http://www.ksre.ksu.edu/library/lvstk2/mf2308.pdf
Different things can cause feather loss. Are you sure it is feather pecking?
Will feather pecking stop at feathers. Sometimes. The danger is that they draw blood when they are pecking feathers and then they really start pecking that raw wound. They can kill a chicken pretty quickly when that happens.
There are different reasons they will peck feathers. Maybe a lack of protein. Sometimes you get one that just likes to peck feathers. Overcrowding or boredom can cause it. Mites or lice can cause it. It is a whole lot easier to treat if you know what is causing it.
Will beak trimming stop it? Depends on what is causing it. It will reduce the chances that they draw blood. Many commercial places automatically beak trim to stop cannibalism due to their overcrowding so in some circumstances it works.
Does it harm the chicken. That is where you get into what you consider harm. Many of the people on this site would be horrified to think anyone would even consider "mutilating" a chicken that way. I see it more as a measure of last resort. If you determine it is one chicken or a few chickens doing it and you have eliminated all possible causes such as overcrowding or lack of protein and they just won't stop, I think your choice comes down to beak trimming or getting rid of the chicken. I personally would eat the troublemaker instead of beak trim, but that is just me.
If you beak trim and do it right, you might need to take care on what you feed the chicken. They may have trouble eating pellets and need mash for example. I honestly don't know but it is something you might want to consider.
