Here are my experiences from a RTW in March, when check-in as a Finnair Silver/OW Ruby for Y class:
- Finnair @ HEL and CDG: priority tag given occasionaly
- Qantas @ DRW and SYD: no priority tag
- LAN Chile @ EZE: no priority tag
- BA @ MEX: "You're not allowed to use the J counter if you're flying Y, even if you're OW Ruby. But as there's no passenger waiting behind you, you won't have to change to the other line"