I've gotten 10.1 up and running on my 8600/300 with stock 604e processor and 256MB of RAM. I'm actually quite pleased with the performance overall, its not that much slower than my G3 350, and it even handles Classic really well. Some things I ran into:
1. I have a Sonnet Tango Firewire/USB card installed - caused kernel panics every time I tried to install 10. Had to pay $30 to Sonnet to get their 10 install util, which worked just fine after the user errors were eliminated
2. My Wacom tablet runs great under the beta drivers now available for 10.1, and the USB ports are (obviously) working on the Tango. I've also got an Epson Perfection 610 scanner, which works great in Classic.
3. As on my G3, OS 10 isn't using my RAM very well. For instance, I'll have ~70MB of unused memory, yet the system is swapping to disk like its going out of style. Go figure. Its worse on my G3 I have a full GB of RAM, and I'll have over half of it totally untouched, yet I'm swapping to disk. I just can't grasp why that would happen.
4. The system will sometimes pause for about 1-3 seconds, then just come back to life. This happens every so often. Not terribly annoying.
5. Here's the BAD part for some reason I can't mount disk images. Disc Copy opens, attempts to mount it, then I get a system dialog box telling me that I've inserted a disk that Mac OS X cannot recognize, giving me the option to Eject, Continue, or Initialize. WTF? I've downloaded a TON of Disk Images, and none of them work. grrrrr. Anyone know a unix-y command for mounting disk images that might be worth a shot?
Other than the disk image thing, this install is very smooth. Definitely worth a shot, even without a G3 upgrade! If you don't have a Sonnet product installed, just use Ryan Rempel's utility. And if anyone has any ideas about how I can get disk images to work, or what might be causing the problem, please let me know!