I've done the WHW wrap many times. Twice for us and about 5ish other times. I really like them. They aren't made for kids who have any amount of body to them though.

DD1 (the first time I made it) has no butt or hips. At 3 she can still wear a size 3 diaper if the need arose. My DD2 is built thicker and they don't fit nearly as nice on her. I think the trick with these is adding extra rise. As written it's really only a perfect fit with a contour (we used Kissaluvs contours at one point). With the extra rise though it fits perfectly over our prefolds/prefitteds.
I've also found that if you think you need a small go for the medium. The front can be pulled tighter if need be so it'll last longer and you'll get a better fit. That said, I don't size up.
