For me there was a big difference: When using the Sonos protocol, I had a lot of skipping and drop-out problems with my Sonos Port. With AirPlay they are gone for good. Additionally, the Sonos App now shows title information and cover art instead of „roon-xyz.flac“.
I cannot hear any difference between the two.
The only „issue“ is a 1-2 seconds lag when starting to play.