I assumed the environmental angle was the reduction in waste going to landfill with all the extra plastic generated, by the diaper and the small bags that are usually used to reduce smell and keep things clean during changing.

The energy saving would not be as clear to me, but i wouldn't be surprised if reusable were a better choice there as well, just not as clear cut.

The amount of waste generated by disposable diapers was a concern, and we tried reusable ones. But they leaked often, the absorption material in disposable ones is way better than the cotton pads you get with reusable ones.

I would be happy with a middle ground. Reusable outer "pants" and a disposable insert designed well to work with the reusable part, as plastic free as possible.