i can tell you right now you dont use your edge in real powder. ever watch yourself turn? your edge just sinks into the snow. your turns are against your base.
then why does your edge sidecut radius make the biggest difference in how a snowboard turns in powder?
when you're hauling ass on a steep powder run you're still using your edges to initiate a carve through the turn.
if edges didnt matter every snowboard would turn the same on powder