That's generally how I've always sexed mine. Pieds can't be sexed visually in the first place, as most tend to keep their spots a lot longer. All babies look like females to start off with. Usually the first molt causes them to start looking like males if they are male, but pied does weird things and they don't always look male after the first molt. Fuzzy, my male pearl, was only split to pied and he maintained most of his pearls for three molts.Behavior alone should be good indicators, they were so obvious that I"m pretty certain.