The main advantage of a dispersive Infrared Spectrophotometer is the lack of KBr optics, which are very sensitive to moisture and need to be replaced at great expense every couple of years. With a wave number range of 4000 to 600 cm- the M530 encompasses 85% of all IR applications, so unless your applications is outside the wavelength range or you need a 3-second scan time, the M530 should be the obvious choice.