I had a brief opportunity to see one of these with the clutch cover off. To my disappointment I could rotate the driven clutch either direction. What NMK describes, when the movable half of the drive clutch moves away from the belt.....free wheel.
Can am uses a sprag on the shaft of the drive clutch that the drive belt rides on. When the speed of driven clutch exceeds the speed of the drive clutch(such as coasting down hill) the sprag clutch locks & engine brake is engaged. As you slow down to a near stop & the drive clutch speeds exceeds the driven clutch speed the clutch disengages. It has worked very well, it needs 100 hour maintenance that very few do. Idle speed must be kept low as well or shift issues show up.
I won't use the term belt slammer as that suggests to me extremely bad clutch calibration. This is the clutch set up I'm very comfortable with, living & riding in the mountains as a sledder. You can calibrate much easier with a wide range of options. So the Can Am is very easy to tune & modify for big wheels & tires, power options etc. Ski Doo is very similar less the sprag clutch.
BS aside the Z1000 clutch set up will let you easily tune area's that is very difficult with a wet clutch. Big heavy large wheel tire combo's can get the engagement rpm moved up with a simple spring change in the drive clutch. You can lower the engagement rpm the same way or if you need a higher shift rpm because you are in elevation & you don't want to influence the engagement......change the spring to a higher finish rate.
The engine brake is a major let down as the sprag clutch is simple & effective. NMK has offered good baseline checks that need to be right, I would add clutch alignment with tight belt shimming of the drive clutch movable half.