http://home.earthlink.net/~gamba2/os8_se30.html
WOW!
Yes it works. Your mac will become somewhat slower, but it works. After following that guide some years ago i decided to leave OS 7.6.1 on my SE/30. You may wonder also why there's a guide to install 7.5 if the mac SE/30 supports it natively.. well it's the IIfx ROM simm.
32-bit CLEAN!
Do you mean slower re: OS8/8.1 or actually makes the machine slower?
This is one of the more exciting hardware mods for Macs. I remember that the oscillator chip for overclocking was popular back in the day as well (not that I would ever attempt it, remembering the prices for Macs back then).
Well, the machine will still run at 16MHz, but OS 8.1 is too heavy for it. It's like comparing the snappyness of System 6 against 7.5.5. If you have a PowerBook 1400 it's almost like comparing the boot time from OS 7.5 on it against OS 9. In fact, the SE/30 may boot faster OS 8.1 than a PowerBook 1400 running OS 9. Now i am tempted to do the experiment.