I've read both and still refer to TLPI as the bible. But if ever a subject needed an ELIF version, it is this one
I could see there being space for a book which covers new(er) kernel mechanisms and features, but as you said TLPI is the Word and if your book covers the same content it doesn’t add a lot of value.
TLPI is ELIF version though
APUE is a National Treasure, but I think LPI has long surpassed it as what you should keep within from your desk chair. LPI is a goldmine and the gift that keeps on giving, but this book looks like a nice easing into it. Instabuy!