Stable not in terms of extensions (they really need to get better at that), but in that if a feature doesn't make a version it gets pushed to the next one. A given version of GNOME is typically very stable in my experience, so long, as you said, you don't touch it. A server with a GUI it not likely something I am going to spend a lot of time mucking with the file manager. And I'm with you on the Files app, it is my least favorite part of GNOME. I typically use KDE, but in RHEL environments GNOME is the assumed DE.