A good scanning electron microscope is not measured only by its ultimate resolution but often by its flexibility as well. In the real world not many samples require their surface to be examined at 100,000X to 300,000X. Other real considerations are its analytical capabilities, such as EDS and WDS for chemical analyses and its flexibility to handle odd samples or odd applications, such as STEM imaging, electron channeling, cathodoluminescence, etc.

Have you ever wished that the lowest magnification of your SEM wasn't 10X or 20X, but rather 5X or 2X or 1X or even lower? This can be especially useful in a forensic application where large samples are common and cutting them or using other destructive techniques would render the sample useless in court.