Then wouldn't it also be fair to say: even with pretty massive changes in fiscal structure, the changes in mobility would be quite modest (at most) and that smaller, more likely changes in FC will have imperceptible effects on this outcome?

Q on magnitude: "..we estimate that a one standard deviation increase in county-area fiscal centralization is associated with 10 percent of a standard deviation less spatial inequality..." Is this: 1 SD in FC associated with 0.0042 change in the level of outcome? (SD of mobility is 0.04 X 0.1)?

Here are some I have used from econ for teaching purposes aside from LaLonde: Fraker and Maynard (1987, JHR); Heckman and Smith (1999, JEP); Cook et al. (2008, JPAM). In other fields: Heineken and Shadish (1996, Psych Methods); Glazerman et al. (2003, Annals); Shadish et al. (2008, JASA).