Nice and clean construction there, glad you got it working. In answer to your question about consistency and the fully charged 18650, yes regulated is better. A big battery that can supply the current should be good from full to about 3.7v and then it's too much effort. This is basically true for all systems, not unique to a genisis. Smaller cells that are high drain will work similarly, but not last as long. A regulated mod doesn't have to be big either, but that longer lasting part does require more sizable batteries.
An easy fix for you would be to use that same mod there with a 18490 IMR and a Kick module without any further modifications, but I have heard it is not very long lasting/ efficient. Also it is not exactly cheap. If you are willing to build something yourself a regulated battery mod can be much smaller too.
I'm surprised you are liking the #200 mesh, I am curious for your comparison to #325, is this from themeshcompany?