Well I've always been super sceptical about people saying they can feel one fuel is better than another but have always ran vpower in the 200 and I filled up with nitro the other day and its definitely different. Better mpg than normal vpower, exhaust sounds louder and car feels more eager.
Used a couple of tanks now and the engine does sound a little big more sporty but that might just be a placebo effect. It certainly seems happier than on 95ron fuel
So NA cars never suffer from knock? It'd be impressive for a person to feel the difference in any car, I doubt you'd feel any difference in every FI vehicle either.
There's plenty of experience with people using 99 over 95 and finding them running better both cold and hot.