I can tell you first hand that I went from a 650sx (which at the time I absolutely loved) to my 90 SN with slight mods and it was one of the BEST decisions I've ever made. Initially I wanted to stay with Kawi because I loved my 650sx and 550sx so like you, I thought of going to a 750sx or sxi or sxi pro, but because of the gazillions of people on this site and pwctoday saying over and over and over and over . . . . to convert to a superjet I decided to get a SN instead. Like I said, one of the BEST decisions I've ever made. I have no interest in ever riding another kawi standup now.
So I guess I can be added to the "used to ride kawi standups, but now that I have a superjet, I'll never go back to kawi" list. Which probably has a least a million people on it.