I haven't tried any of the dry diapers and I'm not sure if you were just looking to try the One-Size to just try another diaper or for the dryness aspect but if it's for the dryness you wanted then remember that you'll likely have to cover it up anyway in a nighttime diaper. The One-Size dry isn't any more absorbant than any other of the One-Size diapers so for nighttime you'll likely have to add a liner or two to boost the absorbancy. By doing so you're covering up the 'dry liner' on the One-Size, rendering it useless as it needs to be in contact with skin to work.

One thing though, leaking even with two prefolds is a little unusual, even for heavy wetters. If you're using the preemie/newborn prefolds maybe it's time to move up a size as those are really pretty flimsy... Two infant prefolds should provide plenty of absorbancy even for a super heavy wetter (theoretically they should absorb about as much as he'd pee in an entire day!!!). I'm thinking the problem isn't so much absorbancy but some kind of fit problem that's causing leaks.

What kind/size of cover are you using? How are you folding the prefolds? If you're just trifolding and laying in a wrap the problem may be that the prefolds are so thick that the cover can't 'reach' all the way over them to cover them completly around the crotch area. Then onesies or pjs can creep inside and wick out moisture. A different fold may help by spreading some of the fabric out differently to reduce the thickness between the legs. A different or bigger cover might also help. Same with making sure that the pjs or especially the onesies aren't too snug as that might make them more likely to creep inside the diaper. A fitted diaper like the One-Size or Sandy's might also help since some of the absorbancy is around the hips instead of all being between the legs. The bamboo might be something to consider as well. It's not necessarily more absorbant (the fabric is more absorbant but they make the diapers trimmer so the absorbancy is the same) but because it's trimmer you could add more to the diaper without making it too bulky.

Karen.