The label on Tec 27 also reads like more than "slight A-1", given color touch, spine split sealed, cover cleaned, etc., but as noted, the market will determine value. If I had the moolah, I'd certainly go after it!
As for restoration vs. conservation, it does seem like splitting hairs. Whatever it's called, the process clearly isn't adding dollar value these days, as lou_fine points out, but in many instances it is adding physical longevity (another form of value) to the books, which many (all?) of us might agree is extremely valuable -- as Punyhuman says, having a book with slight or moderate (or even extensive?) resto is better than a book falling to pieces, and helps preserve the book. Given the increasing scarcity and naturally crumbling condition of these venerated GA beauties, I would think that more consideration be given to the role, "value," and implementation of restoration techniques in the funny-book business... as it has for many centuries in the "fine art" world. (FYI: no conflict here: I buy both universal and restored books, and I have no clue how to restore a book!!)