<font face="Arial, Verdana">Turning on laser mode and doing z moves is not strange in my opinion. I have a delta printer and i can image that you change the height to burn the next layer (change the focus point).</font>
Also in my case m3 s0 or m3 s255 and m5 gives all the same result for all moves! Laser is turned on.
Also laser is turned on during the whole time in this script no change at all!:
<font face="Arial, Verdana">m452</font>
<font face="Arial, Verdana">g28</font>
<font face="Arial, Verdana">
</font>
<font face="Arial, Verdana">g0 z400</font>
<font face="Arial, Verdana">m3 s0</font>
<font face="Arial, Verdana">g1 x100 f1000</font>
<font face="Arial, Verdana">m3 s255</font>
<font face="Arial, Verdana">g1 x-100</font>
<font face="Arial, Verdana">m5</font>
<font face="Arial, Verdana">g1 x100</font>
<font face="Arial, Verdana">m3 s255</font>
<font face="Arial, Verdana">g1 x-100</font>
<font face="Arial, Verdana">
</font>
<font face="Arial, Verdana">m3 s0</font>
<font face="Arial, Verdana">g0 x100 f1000</font>
<font face="Arial, Verdana">m3 s255</font>
<font face="Arial, Verdana">g0 x-100</font>
<font face="Arial, Verdana">m5</font>
<font face="Arial, Verdana">g0 x100</font>
<font face="Arial, Verdana">m3 s255</font>
<font face="Arial, Verdana">g0 x-100</font>
<font face="Arial, Verdana">
</font>
<font face="Arial, Verdana">g28</font>