I have a couple of wonderoos, a couple of Nature babies stuffables, and a slinki minki.
The wonderoos I've used with their own inserts, the others I have tried stuffing with Mother of Eden inserts, old prefolds, and even plain old mf cloths. All of them have leaked. I've heard good things about bumgenius, but I'm soooo unwilling to spend any more money on pockets given the experience I've had so far.