I've been drifting my car pretty hard recently...
My compression on my supercharger won't go above 9psi.
It usually goes up to 15+psi (over sized pulley)
I checked the dipstick on my SC oil, and it is grey, not clear. Most likely ground up gears.

My question is, would it be wise to keep driving it until I fail the SC completely?
I'm planning on getting a new SC instead of rebuilding this one. Just concerned if a failed SC could damage the engine.
I'm not familiar with how these SC work/fail.

Thanks!

The SC12 is a pretty basic piece of machinery. Two rotors timed
together by gears and driven by a pulley. They don't seem to be designed
for taking apart and repairing... I think they were made to last as long
as the engine in normal use, and then junk the car.

If you don't hear any clunking, rattling, screetching, squealing, whining,
moaning, humming, whistling or singing off-key, the chances are you lost
a bit of the "plastic" coating off the rotors. That will drop the boost
by allowing leakage between the rotors and the casing.

If you can't hear any bad noises, and you can still spin the charger easily
by hand, it should be safe to use. And if the charger does stop suddenly,
the engine will still drive OK if you take the belt off. Just turns it into a
low compression 4AGE

One other possibility would be if the electromagntic clutch was worn to
the point where it was slipping under load. I would think that you should
be able to see some heat effect on the outside of the clutch, or smell
burning after hard use.

I'd still recommend that you line up a replacement

Cheers... jondee86

PS: I think you are supposed to change the oil every now and then

I would say clutch slipping or belt slipping is the most likely cause. In this case service will save the supercharger from further damage. The clutch slipping could cook the supercharger bearing and overheat the internal lobe bearing.
If you don't care about any of these things then you could run it till it dies. Just remember these superchargers are getting rarer, more beat, more expensive and harder to find. If you are dead set on staying with the SC there could be the day down the road when you regret cooking this supercharger.
Of course converting to turbo would solve a lot of problems.