TP,
It sounds like you have experience with the M3 delay. Is this something that is well known? If the M3 delay can't be fixed, I'm going to abandon this method of control and look for another method of control. Do you know if this is part of Mach3 or some broader issue?
As for CV mode, how would the CV mode be used to produce a relationship between spindle speed (laser power) and feed rate?
Thanks,
RJ