Besides BerryPlush, Sugar Peas also makes an ai2 system. Wool or fleece cover with a snap-in dipe. I actually like their dipes better because they resemble a fitted a little more closely (whereas the BerryPlush are just a rectangle, sort of like a doulber that snaps in), so I feel like they get better poo containment.
i think the GroBaby's are an ai2 system, too, but don't quote me on that, it's naptime and my postpartum brain is a little foggy!