Thanks for taking the time to comment. On the issue of the debate on external validity, and whether it's getting tiring discussing it only in the context of RCTs (or the new empirical development economics), we can set aside all the stuff from the past two years (including repeatedly on this blog) and see this symposium from the EPW, which includes contributions from Banerjee, Bardhan, Basu, Kanbur, and Mookherjee: http://www.arts.cornell.edu/poverty/kanbur/NewDirectionsDevEcon.pdf
That I wrote a 1,500-plus word blog post isn't indicative of a yawn, but rather the disappointment of hearing the same arguments on external validity, almost exclusively made as a criticism of experiments in economics (glad to say that the paper covered above is not one of them). The more serious work addressing some of the important issues surrounding external validity (three of the papers cited above and some, like Aronow and Samii, cited within the Pritchett/Sandefur paper) is suggesting so far that there is nothing simple about external validity for policy making.
I believe rigor, and not the lack of it, is what makes (or should make) us humble about the limits to which we can give policy advice based on the extant evidence. Development practiced as cookie cutter advice to policymakers is potentially the worst kind. The evidence doesn't tell you what you should do, but rather gives you the frame within which you should consider your problem and the potential solutions.
We'll be looking for your contribution that is neither weak nor ignorable: perhaps it can even be a new entry into the next edition of Mostly Harmless Econometrics...