Ease of Use:
Having a great Geiger counter that is a pain to use is no bargain. Some Geiger counters use a push the button to rotate through menu options to select different modes and ranges. If you read the reviews on these types of Geiger Counters most customers find this type of menu selection frustrating.
The engineers at Images SI Inc. looked at this modality and decided against it.
Look at figure 24, all models can be easily selected from the front panel switches. Another option that received bad reviews are membrane switches. The advantage of membrane switches are they allow a flat profile on the Geiger counter case. The disadvantage(s), the microcontroller needs to see the key press when it is pressed or the option pressed is not initiated. And they don't have the positive feel of a standard switch closure.
You want a Geiger counter that is easy and intuitive to use. Not one that requires you to reference a manual to make mode selections.
The standard warranty is one year parts and labor for any factory defects. An exception to the warranty is the GM tube which is fragile and could be broken easily if not handled properly.