I think someone should sit down and actually try to find out what power/speed works. At 6% power on a 40W machine, I can't imagine this being worth the savings. Cermark would be over 6x faster to mark. That's considerable. A 10 minute job would be over an hour. The difference in actual cost might be $.50 in that situation. So you're losing out on a potential profit, assuming $2/min, of $100 to save $.50. I just don't see the sense in it.
Something to use in a pinch? Absolutely. Better idea? Keep some Cermark on the shelf.
Equipment: IS400, IS6000, VLS 6.60, LS100, HP4550, Ricoh GX e3300n, Hotronix STX20
Software: Adobe Suite & Gravostyle 5
Business: Trophy, Awards and Engraving