I agree that everything should be field tested, but when comparing instruments they need to be tested to a standard. If they are not tested to a standard, it becomes a relative test. Consider this, is the leak detector cold or is it just used in a cold environment, if only used in a cold environment, how warm is it before it comes into the cold environment, how long is it used in the cold environment. If it is pre cooled, how cold is it and what type of batteries as that would also affect the test. If you can describe a test that you would like to see that is repeatable, I would be glad to see how the detectors perform.
As Fieldpiece manufacturers most test instruments they make for the HVAC industry, it was a fair test. That is the environment that they will likely be used.