I’ve used it before for engraving. Just never cutting with a CO2 laser. I’ve had everything from a 35W to a 100W CO2 and cutting it was out of the question.
It’s really good for engraves. You can do similar work on other metals using Cermark (used to be able to get Thermark too but Cermark bought them). Brilliance and Laserbond are also used for the same kind of thing. The sprays provide the coating that the thermal action of the laser causes to blacken and fuse to the metal. Alumamark has that already in its finish coating so you don’t have to spray anything on or wash it off when you’re done.