The timing of this document is excellent! Just last month I was saying "I hope they release and update to the YZE SRD soon. I'd like to see them incorporate some of the newer stuff." I read through the SRD quickly over the last few days. All in all it seems to do a good job picking and choosing from the different systems without just throwing the whole kitchen sink at us. If I have time I'll give it another read to look for typographical errors or minor inconsistencies.
I was surprised to see the omission of base/stronghold/vault mechanics given that they cross (at least) Mutant, Forbidden Lands, and Twilight 2000. There seems to be enough similarity between those three systems that an approach similar to the one you took to talents might make sense. i.e. "Here are the core mechanics and a dozen or so possible structures although your game will likely have many more." I assume the omission is intentional, but I'm curious at the rationale?
Parting thought: will you be issuing an editable version for those of us trying to cobble together our own Franken-systems based on this text?
Thanks,
Jon