Infra red is used in laser cutters because CO2 lasers are efficient and cheap, not because far IR is best for cutting (although its good for organics, its poor for metals). If you go for a diode
then IR means near IR anyway, not far IR, so its not the same and efficiency is more important I suspect.
CO2 lasers are poor at deep cutting due to CO2 in the slot absorbing the beam before it can
reach the material - not an issue with visible light.