So, back to the OP’s original question… is the Neje A40640 laser module any good or not? Given a couple of days to play with it… I say “Yes!”
It’s performance far exceeds any other diode laser I’ve ever had… and how long it lasts remains to be seen. After a bit of testing to find best cutting speed for 3mm (1/8") birch ply, I was able to cut everything but the heart-tree in the following photos in a single pass at 200 mm/min and 100% power… the heart-tree required 150mm/min and 100% to get all pieces to fall out without breaking small branches.
In addition to the air-assist mod we’ve already discussed, I’ve discovered that small 40mm x 40mm x 11mm CPU heatsinks make a great “bed of nails”…
They’re very effective and are easily spread around to support any size workpiece… and a bag of 10 heatsinks is reasonably inexpensive to solve what in the past has been a nagging problem. I’m hoping they should be easy to clean with a cleaner of some kind… any suggestions?
These cuts are easily done with my CO2 laser and much faster, of course. But this diode laser setup is IMO much easier and convenient to use and not so slow as to be “painful”… i.e. the ~140mm x 140mm heart-tree took only 33 minutes, and way less for the other pieces. I’ve also cut several ~5mm materials in my testing as well… some in one pass and others with only an extra pass or two at most. Numerous videos are out there showing folks cutting far thicker material than that… so I’m really looking forward to playing with this Neje A40640 laser module further. I think it will really “up” my daughter’s game when I’m ready to move it to her machine… 
Again… my $0.02.
– David