A: I recently received that question from a customer trying to decide what to buy. I think it's a common sentiment from parents looking to switch to cloth. In the beginning, I myself looked closely at all-in-one diapers before settling on mostly pocket diapers.
As a one-piece, very-like-a-disposable diaper, all-in-ones are attractive for parents looking for the ease of a disposable and the reusability of cloth. They are easy for caregivers and require little explanation.
On the downside, lots of sewn-in layers mean longer drying times. Some, like Mommy's Touch, are designed with flap-like soakers, but they still dry faster in the dryer. Those looking to preserve elastic or hang-dry may not prefer the all-in-one design. Bottombumpers soakers snap out, so this is a nice compromise.
It's harder to customize the absorbency on some styles. bumGenius and Drybees have pockets to add absorbency, and it's possible to slip a doubler in the layers of the Bottombumpers soaker. Otherwise, it's necessary to lay a doubler on top.
All-in-ones also tend to be more expensive, which can deter parents interested in cost savings. Overall, I recommend all-in-one diapers as a part of a stash rather than the whole thing. I do have a few customers that use them exclusively, but for most the advantages of other styles make a combination the best way to go.