I think the magic of the "Cut n' Choose" method is it's simplicity. By the time we get a ref and tell our favourite features.. jeez, the ice cream would be melted.
What I do with MY kids is slice as much as I want to give them. If I get any complaints, I say "Life isn't fair. If you don't like the cake, I'll eat it for you."
"Life is hard. Get used to it. Suck it up!" Hahahaha! It's funny because it's true.