Turning a Redsail 100w Laser into a 40w Laser - Requirements

I have 2 Redsail Lasers, both 100W and thinking of tuning one of them into a 40W so that I can do deeper engravings into MDF.

3 Reasons why I'm wanting to do this,
1) I get to have both Lasers running RDWorks compared to buying a New 40w Laser running other software.
2) I get a work area of 900x600mm compared to the tiny and useless area that the 40w Lasers have.
3) Cost to replace the 40w Tube each time is a fraction of the cost of the 100w

My understandings is all I would need to do is Buy a 40w Power Supply and a 40w Laser Tube, shouldn't be any need to touch the motherboard/Software side so am I right or way off?