Like most others, I only use the clutch for 1st to 2nd gear changes (and 2nd to 1st) - otherwise IRS clutch less all the way.
I've done this on all my bikes over the last 37 years and whilst every one has been a joy on up shifts, a couple have been pigs to master on downshifts (older Honda SOHC fours were the worst).
Downshift wise, my RSV is the easiest for a beautifully smooth shift and I reckon the Fazer 600 is the easiest (non 2 stroke) for smooth up shifts.
It's all about matching revs and throttle, together with a quick "snick" of the pedal.