Obviously nose shape is only one aspect of an efficient design in any type of surf craft and can't be isolated.
All other things being equal though a Full nose will never work as well in the barrell as a finer nose IMO. You can talk all you want about the 12 inches width back from the 'imaginary point', but a nose that is 'cut off' say 6-8 inches back from this will generally not have the same amount of lift.
SUP moves are starting mimick high performance short board surfing which involves turning off the top of a wave in a tight arc back into the pocket - once again harder to do on a fuller nose with less rocker - all other design features being equal.
I understand that this is a touchy subject for some especially when big companies invest lots of time and money into pushing a certain design. As Hilly said, both designs have a place - horses for courses. It still astounds me what guys are using at places like Chopes though!
BTW I have no financial interest in anything to do with SUP, just spent 20 + years working in the design of surfcraft and can tend to crap on about this a little too much