Andrew, I’m a little late to the conversation, but I very much like this layout — innovative and practical, aesthetically pleasing. I’m the publisher for Thomas Nelson Bibles, working on NKJV and KJV. We recently commissioned translation-specific, custom fonts for both the NKJV and KJV, and we’re in the process now of creating entirely new lines of text and reference Bibles. The NKJV editions will start rolling out in January of 2018, with some very nice single-column reference Bibles (with x-refs in the outside margin) appearing in the summer of 2018. We’ve not yet gone for marginal subject headings…but this seems very promising! I’ll be bringing this design idea to our team soon. Greatly appreciate your thoughtful approach to the presentation of Scripture — the sacred and the beautiful are connected, and there’s something right about ensuring that God’s true, holy Word is presented as beautiful, down to the fonts and layout choices!