wouldn't you need a higher compression ratio to even use a higher octane? I've heard of rumors of people mixing 87 with 93 for some reason. But I wouldn't run 87 just because our newer bikes 750's and 1k's seem to call for atleast premium now. I remember my '01 600 stating what ever the pump had didn't matter, but the higher compression now these days might have changed that. Maybe I'm just yacking but thats just my $.02 of what i've heard about all that.
The 600s still only require 87 octane. I believe the 750s and 1Ks require premium. Unless you increase your compression or mess with your timing, there is no reason to go with higher ocatne than what the manufacturer recommends.