I got one to play around with it - so far it's ok for utility blade work, not sure I'd use it on a high grade knife.
Plus -
Convex edge
Fast
Easy
Lower speed - better edge
Deltas -
Belt residue ' dust (maybe because it's. New)
Belt tension and blade pressure are new variables - not so easy to control
For putting on a new edge (taking the blade down) it's a dream, for putting that final edge on with a finer grit ... It's a bit tricky.
I'm still learning.. Who knows
I do...
The answer ain't pretty...