I regularly cut leather. I use leather vegetable-tanned, rather tough tooling. Softer tanned leathers tend to scrump from the heat when they're struck by the laser, so that they can be tricky. I believe, although it's a grade, that the burning scent of the vegetable-tanned leather is probably no too unhealthy. Tanned Chrome leathers smell more clearly bad-for-you. Normally I travel to different cities with my travel printers (check this guide) I have access to laser cutters ranging from 50 to 100 Watts. Higher power allows you to cut more rapidly, usually with less smoke and more smoke on the surface.