I use all 3 inserts and after 2 hours it is pretty wet but not leaking - which is fine for me as I change 2 hourly
They are less capable of holding wee - which makes sense cos when you compare how much fabric there is to sop water up its probably half that of something like a BG with both inserts, for me its worth it for the slimness though as she can walk normally and it doesnt sag in the middle where her legs squeeze it down!
Obviously Izzy drinks a far amount at her age, although not sure how it compares to what solely milk drinkers take onboard?