The rider's task when upshifting is to get it done completely smoothly. With a toe under the shifter pulling up not-too-hard, roll the throttle part way off then back on to the correct point as the transmission shifts. It it isn't smooth, you didn't do your throttle action right.
My bike mechanic recommends avoiding clutchless downshifting and avoiding 1-2 upshifting to minimize the chance of transmission damage (except in the winter when he needs the work).
I think Keith Code's California Superbike School teaches the riders to use their clutch on downshifts.
"The actions of riding one lap of a complex circuit with say 13 corners, like our favorite training track, the Streets of Willow Springs, breaks down something like this:
Throttle position changes (including throttle blips) 50
Steering inputs 22
Gear changes 20
Clutch actions (downshifts only) 10
Front brake pulls and releases 14 "
http://forums.superbikeschool.com/index.php?showtopic=75