[smileyman]

The original reason for GP shift is that the old narrow power band bikes sometimes needed an upshift while leaned over. Impossible to do while leaned over on the left side since you could not get your foot under the nearly dragging, no ground clearance bikes of old...It became all the rage since you could continue your drive out of the corner without altering your line.

These days lean angles have grown so great with tire technology that it is really a no brainer, but since engines rev out so much longer you really can carry one gear thru most corners kinda eliminating the need.

I use GP shift although I can go back and forth relatively easily. The reason I like it is that it seems easier for me to bang away clutchless upshifts while pushing down on the lever. Also allows me to click up and out of a too quickly climbing wheelie...