For me, it's the freedom of choosing all of the traits and mission prompts, that really lets me give a large narrative feel to my game while still having just enough crunch.
In writing Underground, I was able to get from idea to publishable product in just a day or two. I credit that ease of development to the fairly structured template that’s provided and the very good instructional text in the SRD booklet itself. I really like that the Push SRD isn’t simply a set of rules – rather, it’s the rules plus deep advice on how to build a game using those rules.
I’m writing version 2.1 of my Heroic Tales SRD now, and I am going to wholeheartedly adopt this approach, even though it will take much longer to get out. I think it’ll just be so much more useful to the end game desginer.