This has been discussed before. You're wasting your money with higher octane fuel. Unless the engine pinks or detonates on the lower octane (it doesn't) using a higher octane fuel will give you no benefits whatsoever.
High octane does not mean more power. More power is achieved by tuning the engine, which usually involves raising the compression which does require a higher octane fuel to prevent detonation.
I think Derek has hit the nail on the head.
It all really depends upon the tune, or state of it.
Seeing as the 803 runs a compression ratio of 11:1, it is more than capable of being tuned (re-mapped ) to obtain the potential of an engine that requires a higher octane rating.
I've come across this many times with other engines,,,, if it runs OK on 91 octane then it may not be tuned to full potential.
At the end of the day, try a low octane rating and if your bike runs OK on it well use it, but, be aware that you could get more out of it with a good tune and the octane rating recommended by Ducati.
Pinging and detonation are usually related to high compression, overheating, or the ignition timing being too far advanced, an engine tuned to run on 91 will have the ignition timing set a degree or two on the retarded side than an engine tuned to run on 95 or 98 octane.
Consider this, Regardless of what fuel an engine is running at a given time, say on a dyno, what happens if you advance or retard the ignition timing slightly ?
The power output increases or decreases accordingly right.
So, if a higher octane fuel allows the timing to be more advanced, what would be the result ?:rolleyes-50: