I mainly got it to see if I could make it useful for engraving powdercoated pedal boxes. I'm glad to report that it works pretty well for that application.

A couple passes gets it down 95% of the way to the bare metal. And then some 90% isopropyl and a toothbrush gets you another 4%. There a tiny bit of material left over which requires some scraping (dental pick) to remove, but it also kind a looks cool as is (sort of "relic" or oxidized).
There's still some work left to do to get the process optimized and tightened up, but I'm really pleased with the results so far.
Some pics:
Laser in action (here I was testing the feasibility of cutting through painter's tape on a bare box to use as a paint mask):

Powdercoated box, fresh off the laser (no cleanup):

Same box, after cleanup (took about 5 minutes):
