Reader Kent has left a very helpful comment. Logos is producing an electronic edition of the Göttingen Septuaginta! There is a pre-pub special sale on for this resource, more than 50% off the retail price. All the currently available Göttingen Septuaginta volumes are included. The only page samples are page images from the printed volumes, but it sounds like the Logos editon is fully electronic, including both the text and the apparatus, with the Greek morphologically tagged. What an excellent resource! I shall have to pinch some pennies to pick this one up!