I tried several times with a range of power settings but could not get the 4.3mm bamboo to cut without way too many passes and a charred edge. I went back to the CNC mill and cut the piece quickly and cleanly.
On the other hand this stuff engraves like manna from heaven.. Bamboo is a grass not a tree so is basically 100% cellulose which when you blast it with 4000mW of laser go crispy really well. Take a close look at the flowers being engraved, some of those are less than 1mm wide.
I am buying 4.3mm sheets from a supplier in Melbourne for about $55 a square metre. Not cheap but great material. The can supply everything from 0.6m to 12mm. I have deliberately not named them so I don't look like a spammer but if you are interested in bamboo supplies send me a PM for details.