Makes a huge difference. I do touring and long distance bicycling (specifically randonneuring, unsupported timed rides up to 1200km). The reduction in mental fatigue because of less wind noise is invaluable. Also, if using bone conduction headphones, you can run a lower volume further reducing mental fatigue. The lower volume and reduced white noise also lower the threshold for situational awareness.

The Airstreamz site has a guide on how to "finger test" if Cat-Ears will be effective with your ear shape and helmet design.