I like your new shelf - looks good and sturdy! I too have my own system for organizing books based on my own weird logic. And somehow, even after years, I know where they are and why I put them in that specific place.
I have to differ on the weight of the book thing though. I'm not big on ebooks, but I adore audiobooks. I read quite a few books from my reading phd lists as I made laps around my neighborhood because so much reading in a chair was killing my back. Now I am addicted to them and even if I do still love to write in margins and underline real books, I read about 50 audiobooks a year I would not get to read at all if I weren't doing that while I drive or cook. Certain ones help me sleep when I need to shut off the internal monologue at 2:30 am too!
Yay! Another audiobook lover! So hard to find here. Been bashed about the head with them by people who find them a waste of time. But I have no time to waste so I MUST also read per audiobook. Plus they make such nice company if you find the right narrators. Friends for life doubled (author+narrator). Oh at least 50 a year (although Knausgaard and Stendhal slowed me down, and the planned Proust may too!), easily. Prepare 1095 meals to them a year (b'fast, lunch, dinner). Often running 3-4 books at one time! (Alan Watts for b'fast; Nesbo's Macbeth for lunch; Burnt Out Case by Green during my walk (but almost finished so then next A Short History of Tractors - Lewycka), must fit in the last bit of Charterhouse of Parma during cooking, and might wander off into the night on The Silk Roads by Peter Frankopan.)