I just bought some used FB size large from a friend, and they have leaked two times in a row around the legs on my 2 year old (and just now leaking a little poop too, DH tells me). The second time I know for sure that the insert was not full, it was dry at the back and did not feel very heavy. My son is a lean little guy and I had to snap the diaper as small as it would go (in fact the two middle snaps cross over each other), so I am thinking maybe it is a fit issue, but they could also be repelling. They were used and washed every other day for about a year and a half. The outside of the covers look great, but the fleece looks worn and pilled. My son probably weighs about 30 pounds. Any thoughts from experienced mamas on which it is?