I haven't tried 16.04R yet, but I have a few suggestions for 12.04R that may also be relevant to the former...
- Update Yaboot to 1.3.17 over 1.3.16.
- Add windfarm_core to /etc/modules. On USB, my G5's fans were blazing without it.
- I haven't tested, but add pmu_battery to /etc/modules for laptop battery recognition and monitoring.
- Add vm.swappiness=10 and vm.vfs_cache_pressure=50 to /etc/sysctl.conf to make swap management more efficient, especially on machines with less than 1 GB RAM.
- Add Acquire::Languages "none"; to /etc/apt/apt.conf.d/00aptitude to make APT operations faster.
- Preinstall preload to increase speed.
- On 16.04, preinstall Surf and SurfTube so that people have a fast and easy YouTube player, plus a lightweight WebKit browser OOB.
- Remove apps like Simple Scan, and the Penguin games to lessen image size. I'm pretty sure nobody wants to play the Penguin games.
- MX Linux uses sysvinit instead of systemd for its default init, which also improves performance. Maybe you could do something similar, just by installing and enabling it? It may well outright fix the graphical and sleep issues present on the G3 / Radeon machines, so I would at least look into it.
Otherwise, it's an all-around great experience to have (mostly) everything working OOB w/ our great Web browsers already installed. We've got some fantastical stuff here, so thanks again to you (and the rest of us, too). 🙂