And, unofficially, MacOS9Lives can boot directly to OS 9 on FW800 PowerMacs, which have 1.42GHz processors with 2x the L3 cache. Officially, those machines only supported OS 9 via Classic.
I used it to install OS 9 on my G4 Mac mini, and, aside from an annoying bug where the USB mouse is completely unresponsive after booting 50% of the time, it works great.
