I'm not sure how much you'd benefit from rocket league, the extra smoothness might help a little.
Some of the benefit is simply lag reduction.
eg 1/60 = 16.666ms/frame
1/144 = 6.9444ms/frame
Assuming the game pushes information that fast, eg someone pops around a corner right after your last frame and the game is ready to update your next frame you gain a little under 10ms regardless of perceived smoothness or not.
Useful for shooters and anything twitch, the rest is up to how you personally notice the smoothness or not.
It's a shame there are no big pc gaming stores you can go test monitors and mice at