So my friend and I came to the same conclusion independently and I thought it was worth sharing here. Simply put, additional weapon slots aren't worth it, but there is a way to fix it.
Now, I don't mean to say that the slots aren't worth the energy cost, I mean that currently they aren't worth using at all even if they were free. I purchased one additional slot. My friend actually purchased both for a total of four slots. However, this past weekend we only carried two weapons each despite having the extra slots available.
Why? Simple.