I seriously question the utility of the extra material. If it's not just the same mix without vocals, it's a "rough" mix that is more or less identical to the final version. When the Beach Boys did the super box set of Pet Sounds, you got to hear outtakes, live studio arrangements from Brian Wilson, or the incredible Beatles anthologies...I'm just not sure what's really here. It almost feels like Page found "La La" and "Key to the Highway" and thought "this is plenty." And this is coming from one of the biggest Zep fans on the planet.
Admittedly, the 69 concert is a good find.