For anyone who is interested in making a switch to Gentoo, when necessary, I'd like to plug the Gentoo forum and wiki resources as being excellent. If you're reading this on a MATE system that you've setup and enjoyed, you can do Gentoo too! It will take more effort than MATE, but you'll learn so much more about Linux OSes in return. (Sadly, I've forgotten most of it in the last 15+ years and become a lazy Linux self-admin.)
It's really a shame that support for my ppc mini is winding-down. It ran 24/7 for many, many years as both a media server (satellite 4DTV firewire and Ku band digital HD video recorder) and shorewall firewall. Most of my computers have expired into the computer boneyard since I bought this mini new 14 years ago (right from Apple as an Apple developer) but it's still running like a top. Based on my study of its architecture, it's immune to Spectre and Meltdown vulnerabilities too. It's a bit slow to boot MATE, but once it's up and running, it performs most PC sorts of activities with quite usable speed, IMHO.