Just to add my perspective to the question of quantum depth: Q8 is useless even for serious photo editing. Q16 should be the default for "normal" users Q32 is what we require in science when working with scanned fluorescent images. (For example, gene expression profile scanners give 20bit output.)
So, I'd be delighted if Q16 became the default, and would be even happier, if it wer possible to have higher quantum depths as alternative package to install optionally. Many thanks, David.