Ahoy Captain, Very good question, and I am not an expert.
I have a Beneteau 393 with a roller furling main which I brief as 'infinitely reef-able'. The main is basically flat, no discernible bias cut, to facilitate reliable furling through the narrow channel in the mast. An effect of this cut is that when main is furled there is a relatively even load on the luff, no bagginess, therefore no catastrophic load on the foot or luff at the furler.
Yes, a flat sail is marginally less efficient, but no choice on mast furling.
FYI, I permanently marked the topping lift and boom vang lines to insure the correct angle of the boom when the main is furled and have never had the sail over-ride and jam for over 3 years.