I disagree with just about everything you said. GP shifting, as I recall, was developed to allow a hard left turn upshift without having to get your foot between the tar and the shifter which at extreme lean is impossible, hence my smaller foot observation.
Shifting has zero to do with corner speed unless you need to shift as you exit and you can't stretch the gear you are in to a point where you can shift. On the street the point is moot, as you shouldn't be that far over anyway and if you are I guess you need the 0.00001 of a second to get to the next corner that much faster than waiting 30' to shift?
Regardless of our opinions, you have a preference or you don't. Wasn't Kevin Schwantz the guy who ran normal pattern shifting right up at the front of the pack?
This article mentions body rotation being consistent with braking and normal downshifting.
http://www.sportrider.com/tips/146_0809_reverse_shift_pattern/viewall.html