While the effort to add this would be significant, I think it would be very useful for Logos to include the original publication date, or perhaps date of authorship, of a book, rather than the publication of the edition digitized or created by Logos. For example, the publication date for "Grace Abounding to the Chief of Sinners" is 1995, which is not particularly helpful when I want to search 17th century works.
This could, of course, get complicated when the original publication or authorship date is disputed or unknown, but if the feature is useful enough I'm sure systems could be devised to account for such variances.
Would anyone else find this as helpful as I would?