This has been discussed extensively on this, and other, forums. Running higher than 87 is not beneficial in any way. It doesn't have more energy, it won't give you any gains, it'll just waste your money and possibly cause the bike to run less efficiently. The only reason to run 89 or 91 is if you're using an aftermarket fuel management unit with a map that was tuned by the company using a higher octane fuel, in which case the fuel and ignition timing has been tuned to compensate for any differences in flame propagation etc.
It is important to note that the quoted 87 octane number only applies to the US/Canada which use the (R+M)/2 rating method. Other countries may use a different rating method, such as Australia and most of Europe which use the RON rating. 87 in the US/Canada is equivalent to 91-92 RON, so make sure you check the rating method posted on the pump if you're in another country or you may get engine knocking from using a fuel with too low of an octane rating.
I would respectfully point out that this is not the whole picture. As many things often are about internet wisdoms, it is more complex than many like to state.
The first thing is that octane ratings are first and foremost a guide for us about how easy/difficult it is to ignite the gas. Everyone knows that part. There is no caloric benefit to a higher octane. There is a difference however how fast the flame front travels, especially if there is ethanol in the mixture. Thus most of the time one can put in a LOWER grade, even than is recommended and mostly, on todays electronically controlled engines you will not get pinging until extremes are reached. Ever notice how compression has gone up, and with it, it used to mean that you needed an octane boost, but nowadays all of a sudden the same compression often does NOT need a higher octane. As one poster eluded to already the engine management system can take care of moderate levels of sub-optimal ignition. It is how it does it that can be a problem, depending on your point of view. Basically the engine advances the ignition. No pinging - but at extremes I don't think you get full full gas burn, and it leans it out at the same time. Net effect is that you lose a bit of power with engine tech saving our butt. That of course is much better than pinging but you but if power potential goes down, maybe higher octane is net beneficial? It actually gets more complicated than just that, and I don't understand much of it, but as a simple addition to conventional debates it is a small point worth adding.
If you ride a fairly new bike and ride is a relatively relaxed manner run what you want works. As the carbon builds and engine wears (oil burn also affects all of this minutely) or if you ride like a true Green-Blooded-Ninja-Squid, then higher octane is not completely wasted. Besides rubber probably costs more than the premium cost of the fuel.
As far as ethanol, supposedly engines are formulated for it. What I find odd is that different bodies (used to anyways - I don't know nowadays) have different ideas as to how much is too much. That tells me that to some degree it is harmful and so, seeing the fact that I LIKE my Ninja, I pay the extra price and go to the extra effort to find and use the "real" stuff.
Ethanol has a lower caloric value, btw, so if everything was equal there would always be more power in pure gas. But things are not equal. Ethanol is oxygenated and that flips things upside down. You still have less calories so less potential for work, but the flame now burns very quickly and is suitable for very high rpm's and lower emissions. I do believe that all of this goes hand in hand with learner mixtures and so oil is probably much more important nowadays. So go figure, I'm not sure of what final conclusions to draw. It might be worth a mention that Ethanol is hygroscopic whereas gas is not, so adding heet once in a while may be a good idea, or does anyone know if there are additives in the ethanol gas for that already?
I run two or three tankfuls of ethanol free back to back about twice a year in my Miata with its well worn 180,000 engine, ever since my mechanic suggested it, and it really seems to make the engine run smoother and the idle more even. It would never have though that, but I don't think its my imagination, especially the idle which is obvious.
Good topic - I'd love to know more about it.