A metal tube is a huge boon over glass... easy to refill. There's nothing directly preventing you from doing the swap, so long as you realize that most Chinese lasers are typically analog control (i.e., turn a power knob by hand) and not under software control rather than the more useful PWM of most US laser systems. If the replacement tube is able to be controlled with a knob, you're good to go, otherwise you'll need some extra toys. Easiest is to create a small circuit that will provide an analog-to-PWM interface, still not under software control. If you change the software, you'll most likely need to change the electronics, as well, as typical Chinese software is heavily tied to the drive electronics.