SM-g920i - Frequent swapping between OS versions

I currently have an SM-g920i version of the Galaxy s6, and I'm looking to swap between both versions of lollipop and, eventually, marshmallow in order to test for compatibility issues on an application I'm working on. Currently, it's on 5.1.1, and I was wondering if anyone had any suggestions. Based on my reading, I might have issues even going back to 5.0.2 from 5.1.1. I'm likely going to have to swap between flavors on a weekly basis and need a method that's relatively simple so that I can pass these steps on to some more.... technically challenged people.

Thanks.

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