I think another useful addition to the Xenogenic system would be the ability to customize the monster palette. For example, instead of an adventure filled with goblinoid creatures, perhaps the DM would prefer one filled with lycanthropes (were-creatures), or normal animals, or evil humans, or whatever. The organizational complexity is admittedly a bit daunting (because it multiplies the number of customizations by, um, "a lot"), but if this can be surmounted, you would have an even more flexible, useful system.
Thoughts?