I have used 98 fuels since the day i got my license, fuel is never that new and I want the maximum safety blanket that even if i have a bad batch of fuel the octane will be high enough to not cause issues with pinging.
My bike is tuned for 98 octane fuel using a custom map to run between 13.5 &13.1 AFR I have no oxygen sensors so rely on the highest octane possible out of the pump.
Also having had a friend with a Nissan stagea with a fuel controller tuned for 95octane get a old batch a fuel from a server and detonate when coming onto boost (20psi) he possibly woudn't of got the issue if he used 98.
Also when my missus had a new toyota echo in 2003 she would put 91 in it and winge it was running crap which it was (missing surging etc) put 95 or 98 in and hey presto smooth as better.
I use the same servo & pump (caltex 98) as this was the same server I tuned my custom map with.
Only difference I have noticed with different brands is Shell V-power stains fuel bowls, they run a additive which causes a yellowing colour, this may have changed but since a year or to ago. In my last job guys who came in for tunes and said "I always use V-power" tended to have the discolouration.
I have never had an issue with 98 fuels as for increased range MEH but 10% Eth in my work car does reduce its range, ohh i happily put 91 10% Eth in my work crummydore cause i dont care about that.
On the Octane additive I used to have a rodeo 2.6 petrol minitruck which had 1 muffler no CAT (light vehicle law) i used to run on 98 and for awesome P plater hero satus used to put 10point octane booster in and holy crap did it used to shot some flames, out past the tray and all HAHAHAHA ahh to be young again.

Kawasaki ZX-10R 2008 - R77 Yoshi full system, PC3 Custom Mapped, Benneli bar end mirrors, Puig Double Bubble, Radiator protector, CircuitOne Mirror blanks, Pazzo levers, Shift-I, etc