Feed back. Why would you want to be fed in your back? The only way to reach your alimentary canal from the rear is the anus, and taking in food as a suppository is going to be painful and probably require assistance. I strongly prefer Feed Mouth.
Also, unless you have a time machine, or are working with an editor, before the story is posted, being told something is wrong is difficult to correct, and people who read the story/posting before the correction is made know about the error anyway. It is almost all feed forward, you get comments after the story/chapter is posted.
Now if the feed back is praise, it doesn't require time adjustment to make any changes, but isn't it strange to ask for praise? I suppose saying you want feedback is more defensible than saying you want praise, but a lot of times that is really what they want. I think it might be better to ask for comments rather than feedback.
If you have listened to a microphone too close to a speaker, you have heard feedback. Its loud and hard to listen to, and might damage the speaker if it is made to vibrate too hard by the noise going through the microphone to speaker and back again and again until something breaks or someone turns off the system, either the mike or the speaker. I can't believe anyone wants that kind of feedback, unless someone wants to shut up a crowd, or make them move away.
End of Rant.
I recently sent this to a certain Corporal, who may want to remain nameless. I looked at it and decided I wanted to spread my (mis)information widely.