This doesn't and wouldn't surprise me. Big key here is you had this clutch balanced and it sounds like you are running a good clutch calibration. Glad you're happy with the ZRP components. But your lightened ZRP parts have a much different effect on dampening harmonics and vibrations than a ring gear. Apples and oranges.
For the masses out there that just ride and don't modify in detail, not very many people actually have their clutches balanced. Would this help? Absolutely. And we know, Polaris Industries doesn't and isn't going to do it with a specific calibration correct for all altitudes. Just another reason why I'd like to see the added ring gear on all clutches.
It's not just about the adding or subtracting mass but the design and location of the added mass and it's location on the clutch assembly. In this case, the added ring gear's mass being much farther away from the center of the crankshaft is going to react much different than your ZRP clutch parts.