Just upgraded 2 Designer seats and 1 Pro seat from 8.1 to 10.5.
Also upgraded all from P4-3ghz/1 gig of ram/XP to i7/12 gigs/Win7.
Worth it?
Everything runs faster, Flexi is stable (not a crash in 3 weeks). Rips faster, print quality is pretty much the same. No problems getting anything running.
I like the direct send to VersaWorks- since I run a Roland, it saves me a few steps on every print job.
Soft shadows are nice.
Update font list without quitting and reloading is a real time saver.
Don't include stroke in measurement is great too.
Haven't had any problems with PDFs as of yet.
For us, all of the upgrades were totally worth it.