I agree that for most conditions you can keep the reference stance and let it rip. On deep heavy powder days and where you cover large areas of gentle terrain a set back can help a lot. I would set all the way back depending on the board (posi camber).
Otherwise your back leg gets a much bigger workout than the front.
I set my proto just one notch back last time out and it really helped in the 1m deep pow I was riding. Could still carve really well on groomers too.