I know the old view about the eye not being able to see above 30FPS isn't as cut and dried as people make it out to be, but when I had 120 FPS on my 144Hz monitors I can't honestly say I noticed any difference, aside from the much higher temp of my graphics card. I've gone back to ~40FPS and cooler temps.
Give me a shout when higher FPS (or lower ping, etc) makes AD abandon the holy bridge of Alessia and actually attack / defend things that give points.
I can barely see something the size of a planet (for example, an actual planet) at 10 paces. Medical science needs a few hundred years before it can help me.
Still, there's an upper limit to what the eye can detect, and while I'm making no claims on what that number is (I don't have any of those fancy new-fangled "qualifications"), I've seen no evidence that you can detect 120FPS when you're looking straight at it. I know peripheral vision can benefit from higher numbers and will presumable help with the smoothness.
I guess what I'm doing here is mocking gamers and their collective dumb obssession with things they know nothing about - "T3h higher numberz makes me better". A perfect example would be lag: taking the blame for the fact that you suck since 5,000 BCE.*
* Also the fact that most of those gamers don't know lag from ping.