we used BM's on Aimie from birth until 6 months and I found them very fiddly.
we never really had many problems with them but OH always seemed to put them on wrong so they leaked every time for him
the biggest problem we had was the wraps because they discoloured really quickly and some of them ended up with their outer coming away from the PUL. I'm not sure how they get on with older babies but by 6 months old the large sized wraps were getting a bit snug on her but she is a pretty big girl (in large everything from 6months
) and they would need to be boosted to cope on her
ETA the picture and also say I found they wee a bit trimmer in the bigger sizes