And the verdict is....

Well...it seems I don't have one! Despite increasing his water intake by a full bottle of water before bed, plus leaving the nappy on this morning by an additional 1.5 hours after he woke up (so 13 hours in total), I could get him to soak through the layers. He barely wet through to the pocket insert so there wasn't any wet bamboo fleece against the embroidery. I'm not sure whether to be disappointed or happy LOL.

It's in the wash now so I'll be reducing the amount of boosting in it and using it with Ryan tonight.