from a quality perspective, test moisture content water activity has nothing to do with the crispness/dryness of your finished goods
Do not waste your time on water activity---all that will tell you is how fast a pathogen can theoretically travel through your product, lower number, less likely, higher number, more likely
Moisture levels on the other hand can capture fats as well as liquid which all contribute to the overall sensory qualities of your finished goods
i.e. a banana muffin where 1 less than usual bananas were used will have a lower moisture content after baking than the normal recipe as less moisture was introduced at the beginning OR exact same recipe, but the bake time was an extra 10 minutes---more moisture will have been lost due to evaporation
the list goes on and on