So far all she has done is get inside it. I got her the regular length. She is really short, and it fits her just right. Not too short or long. Her body shape also must have been what they modeled it after because it is wide and thin in all the right spots.
For kelty sizing, I remember when I was looking at getting me one. I went to REI and tried it on and found a long was just perfect, even though on paper it looked like a regular would fit. So, if you are looking for one, get the size bigger than you think.