The most important factor to keep in mind is the beam diameter of the laser (2-3mm). If I were to focus this laser to a small spot as I would do with my DIY reds (less that 1/5 mm) it would probably get the job done much much faster. Another variable of importance is the cardboard. My reds can burn pretty quickly through the cardboard from a coke box. The cardboard in this video is from the packaging they used to ship the 2 heavy lasers. It's actually 3 layers of thick cardboard, 1 on each side and a 3rd ridged piece in the middle for strength. I tried burning through it with my 250mW red and it took a minute but it did the trick.
The GB for these just ended today. They were 1650 each. Expensive, but One heck of a deal.