Maybe we need a "comfortometer" which measures comfort.

Ideally, it would be a machine into which you insert the pack (loaded or unloaded) and out comes a "Comfort Index".

It could also be a machine into which is inserted a Pack, Gear and a Human Carrier.

Finally, I am offering for sale an "Official Grain of Salt" - a tiny salt container which you keep with you. Anytime you encounter a product rating, you open the package and take your "official grain of salt".

:-)