SuperDo are pricey and not worth the investment. Why spend the money when you can just double-triple-quadruple stuff your pocket diapers and get the same effect, right? Wrong!
A very common culprit, known to cause mysterious leaks is the overstuffing of pocket diapers. Overstuffing basically renders the leg elastic on your cloth diapers useless. The cloth diaper no longer conforms to the baby's shape and the elastic does not fit securely or move with the baby.
Overstuffing causes gaps around the thigh and inner leg and groin area. This is frequently the reason you'll see moms looking for support, they complain "My child's bedding or carseat was soaked and they had on a brand new diaper, even the inserts were still dry! Something's seriously wrong with this diaper." In my experiences, the problem of overstuffing or using the wrong inserts can be the root of the problem.
It's important, especially with pocket diapers, that the diaper still be pliable and not stiff after putting in the desired inserts and that it be able to move with the baby and conform to the babies shape.
In the photo below you can see a Knickernappies OS Diaper stuffed with two micro inserts and a tri-folded prefold vs. a Knickernappies OS Diaper stuffed with a Knickernappies SuperDo insert. Clearly if your pocket diaper is literally able to stand up on it's own, you can assume it's not quite going to go with the shape and movement of the child wearing it and you can also tell that the stuffing will prevent the elastic from fitting securely against the child's thighs.