Great questions Matt. I always recommend the personal branded domains for writers. Oftentimes we as the creators of our projects, brands and books find a theme to be a unifying or grounding force ourselves, but I've found that they usually do little to help forge any sort of connection or bond with potential readers. The personal brand (your name/face, and thus, your story/context) is what allows an otherwise anonymous prospective reader online connect with you on a deeper human level -- the human connection is always more memorable than a brand name or theme.

Also, you have the practical flexibility of using the same brand name for the rest of your life (unless you become a felon! :), whereas you might creatively outgrow EmpiricSpirit someday! I'd recommend the personal branded domain.