In the first ever performance group I participated in, it really did boost my confidence while I was doing it, but it was short lived. I was an On1 dancer at the time, and the performance choreo was On2. I learned the choreography and was able to perform it flawlessly, and so I felt I should be able to dance On2 socially. Boy was I wrong. Choreography did nothing to help me with improving my social dancing skills. I still couldn't dance On2, and I had to learn it through social dancing and by locking myself in a room and re-learning every step for a good 3-6 months before I started to feel comfortable with it.
I find that some beginner/intermediate performers have a tendency of locking in their movements, which carries over into their social dancing. This means that when I try to execute certain patterns with them, they will always complete their choreo, even if it's impractical to do so (ie. when the music is too fast). It drives me nuts some times. If I ever learn another piece of choreo, I am going to express myself however I feel like (which would make me a terror to choregraph for). I realize this may translate to a less than synchronized look on stage, but I prefer watching natural movements that reflect someone's ability to express the music rather than an identical set of canned movements. Of course, beginners usually want to know exactly where to place every body part, so this gives them a more mechanical look. In the end, this could have a disastrous effect on their social dancing.