First off I have never owned or ridden a Sidewinder. My only experience is my Turbo Viper. The biggest problem I see is the bulk of the weight is in the front. Even with loosing weight from mods the front is always going to be heavy and be out of balance. This is just my experience on my sled.
Forsure , rest of chassis weighs same as cat. I’ve never rode a viper but from the guys that have the Sidewinder and viper aren’t even in the same class on how they handle.
Too bad Yamaha doesn’t do the demo rides in your areas, be great to see your opinions after riding one.