this is great. i realized that manuals and documentation might have used a lot of paper back then. the new PDF that was typeset using troff is half the length of the original!
I don't think so. It's exactly the same as the original (give or take fonts). The original you see is a daisywheel printed version, so much less dense. If someone had output the doc on a phototypesetter way back then, it would have looked much the same as the "new PDF". fwiw the main point of developing Unix was to facilitate this kind of "room-top publishing".