Have you tried it? I just installed gamescope and launched some games with it via steam launch options. So far I feel like the frame times are better. I use it on top of KDE and with an AMD card. Freesync in Gamescope works too. (Have it allways on in KDE if that matters).
I do. But as a session for Big Picture Steam. It’s great as it enables HDR for me. I supplement it with gamemoderun as a launch option to optimize it even further.