For me the golden rule is to buy the best available. I'm a full throttle rider - not all the time but several times per tankful and I want to not think about the fuel when I go for it and need it. My wife also buys the best she can for her supercharged car (and temperamental '77 Sportster).
In the UK we use some cruddy RON status rather than MON and I always go for 99 RON in preference to 97 or 93 or whatever vinegar they want me to buy.My message - if you can use the throttle buy the fuel. If you ride "fluffy" who gives a sh*t what fuel goes in.


Shell do V-Power 99 Ron stuff but BP don't and BP seems too salty for me just now.

 

Modern knock detection senses ping well before it's audible to human hearing. I guarantee that if you are running the lowest octane and running hard on hot days that your engines are detecting knock and pulling back timing/enriching the mixture but it's all happening before it reaches the point where you'd notice the ping.

High octane is only a "total waste" if the engine isn't tuned to use it. The "famous engineer" (whom you conveniently don't name and don't provide a source for) may have been speaking for cars not tuned for high octane. Or he may have simply been pointing out that, since most modern EFI systems can accommodate lower octane by retarding timing and running rich, running low octane won't hurt the engine. Calling high octane a "total waste" in an engine that is designed to be able to take advantage of it is no different from calling the Corvette's big V8 a "total waste" unless you're on the strip or on a track.

Some people may consider it a "waste" since you don't "need" the extra power, but IMO it's worth the extra 20 to 50 cents a tank to be sure that I'm always getting full power. I don't "need" it, but I paid for it when I bought the bike and I damn sure "want" it.