I bought a quickshifter from SBS and it was certainly one of the best purchases I've ever made for any motorcycle. And it does seem to help with downshifts as well. That could be placebo though.
Even before the QS I hated to pull the clutch. Once you train yourself to not use the clutch it's rather simple and seems to keep me more in tune with the bike. Which is also placebo probably.
Certainly can't chastise anyone for using the clutch though. If you miss a clutchless shift it feels like you've f*cked something up. But I've done it dozens of times with no issues on any bike I've owned.
'09 Honda CBR1000RR Repsol
'13 BMW HP4
09 CBR Repsol NADA $8865
09 CBR non-Repsol NADA $7605