Originally Posted by david_z
This, pretty much. Also the 154 will weigh different from the 157 and the medium bindings less than the large, etc. so then you start worrying about the entire matrix of weights and surprise next thing you know you're snowboarding's equivalent of a weight weenie
It's easier to just leave your wallet in the car if you want to shave a few grams, or drink one less beer, etc.
Are there differences in weight between items? Absolutely.
Do these difference have much or any effect for the vast majority of riding? Absolutely not.
Some of the other variables that are not specified would be much more useful - min/max width at the insert pack, mm of camber when unweighted, etc.