We all have individual views on the use of higher octane fuels. In Australia AFAIK none of the fuels, regardless of octane, has ether content (MTBE, ETBE, TAME etc.), so unless we make the mistake of buying fuel with ethanol content, we do not have problems with fuel stability in storage. I use petrol that has been in the can for five years with no difficulty. Ethers and other oxygenates (chiefly ethanol or methanol) are widely used in the US, and cause a multitude of problems, as well as increasing fuel consumption (oxygenates are fuel diluents: they all have to be mixed with air at lower air/fuel ratios, so you use more fuel per kilometer). The addition of these substances to fuel is not done capriciously in the US, it is done because air quality agencies have determined that there are exhaust emissions advantages from their use, which has become mandatory in some jurisdictions.

Because fuels containing oxygenates require richer air/fuel ratios, they only work correctly in engines either tuned exclusively for their use, or having closed loop mixture control via an exhaust oxygen sensor.

Note that Australian fuels are labelled based on their Research Octane Number (RON) while US fuels are normally labelled based on their "Pump Octane", which is simply the numerical average of their RON and their MON (Motor Octane Number). MON is always somewhat lower than RON (unless you are testing pure Octane, a common fuel constituent), so Pump Octane is always lower than RON. Bear this in mind if you are ever driving in the US: there is no benefit in filling the majority of cars with fuel marked as 91 octane; 89 is perfectly adequate for them, since it is about 91 RON.

The traditional refinery practice in Australia in the day of leaded fuel, was to stream regular octane and premium octane fuels separately, and add approximately the same amount of Tetra-Ethyl Lead (TEL) to each. In the US it was much more usual to add varying amounts of TEL, to provide the chosen octane level. This Australian practice of streaming the fuels separately through the refinery is still practised AFAIK, and as a result fuels of different octane levels have different constituents. Some of the high octane constituents are used in higher concentrations in higher octane fuels, and some of these constituents may be somewhat more likely to form carburetor gum.

Personally I always use 91 RON fuel in any engine approved for 91 RON (89 octane if the handbook is prepared for the US). Aside from saving money, this gives me reasonable hope that the rate of gum formation will be lower. There are no functional advantages in using a fuel of higher octane rating than the engine's requirement.