I don't subscribe to the bigger RON / better fuel theory, but I do know most on here prefer the 98.
The wife believes she gets better ecconomy out of it.
The stock
ECU may well be set up for 95 RON not 98.
The extra resistance to detonation of the 98 may infact be a real player here.
Early days yet. Could be a placebo theory..Time will tell.
Keen to hear of other peoples experience though.