These days, engine management systems are quiet clever (I believe). The better the fuel you put in the tank, the better, and more efficient the engine runs. Remember, RON 95 is the LOWEST that the bike will run OK on. On RON 98, it runs (or should run) much better.
I use 98 and my fuel consumption seems to be better, and the bike seems to runs better - so my CT seems to prefer it.
However, it may be all in the mind.
I think the extra 50p extra a tankful costs is worth it