Having studied Classical Greek, Latin, and Hittite, I can vouch for the dramatic difference in the way they express subordination. Hittite is definitely simpler—in that area, anyway!
But it got me to thinking about discourse analysis and Aspect/Actionsart/Tense/Mood and the ramifications this has. No ideas yet, but just food for thought.
By the way, this is a wonderful book. It's making all kinds of stuff that I've noticed in the various languages I've studied over the years fall into place. Of course, there a paragraphs where I get to the end and don't have a clue what they are saying. Sometimes I wonder if it is even English!
[Updated 13:20] I added Mood to the Aspect/Actionsart/Tense because in Greek it is a sequence of mood, not just tense. I hadn't thought of that at the time of writing. So, it gets even more interesting (or less to some) in that you now have the whole TAM spectrum involved...