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Idk.
I almost always put it in my 900, just because.
There have been a couple of occasions where I needed fuel and had no option so I topped up with enough to get me to premium petrol station. I didn't notice a massive difference - or enough that I could definitively say it wasn't psychosomatic - but it's not ££££s like a 50l car tank, so I've continued with premium.
On my 125cc it was 100% noticeable. It simply ran better in every way.
Someone with plenty of bike years advised me to use better fuel and was the one that told me the smaller the engine the more important it was. Once I tried it, switched to regular to double check, then switched back to premium I never used anything else in that bike.
Fwiw there was also a noticeable difference if the tank was running low, so I'd try to keep >¼ of a tank. So on balance I've assumed smaller engines to at least "feedback" their grumbles more to the rider, or possibly just be more sensitive to any performance enhancements.
Wait what?! Should I be putting the fancy fuel in my 600?