The Wilber-Combs Lattice was formulated to address a problem the standard linear model of stages (the "levels" of AQAL's quadrants and levels) had in addressing states of consciousness. And that is that people from any stage of consciounsess have experiences relating to any level or state of consciousness. Therefore, an extra parameter, of temporary states of consciousness (horizontal axis) was added to the permanent structures of consciousness (vertical axis)
Obviously this is not yet the whole picture. For one thing, reality and evolution are multi-faceted, multi-dimensional, and branching and converging, it isn't just a simple linear spectrum a la Great Chain (metaphysical) / Great Nest (evolutionary/holistic) of Being. i mean, it includes that as a generalization, but is not just that. For another, evolution proceeds organically, and cannot be simply mapped on a cartesian grid. But it is certainly an improvement on the previous model
Ironically, I would present this diagram at 90 degrees to the Integral Theory version. For me, evolution (i.e. permannent structures of consciousness) should be portrayed horizontally, whereas states of levels of consciousness would be portrayed vertically. This shows the difference ion perspective between Wilber's point of view and my own; Wilber tends to privelage developmental psychology, whereas I prefer metaphysics.