Continues of Muslin Prototypes

I've made two muslin jackets in progress. (One jacket has a zippered sleeve.) My next steps are to address two assumptions:

1.) Will two jackets provide a compare and contrast to user testing rather than one with just a zipper. Should I also simultaneously test the ease, functionality, and performance of my jacket with "new closures" to the user? 

2.) Is there a way to find modular jackets? Can I use data (gesture, movement) or pattern making techniques/tutorial to imply a modular jacket that can be customized?

I am planning to apply an accelerometer to track gesture and movement of a user donning and doffing the jacket. I will finish adding sleeves to the jackets as well.