In the original draft of the motion, there was no adjustment for median family income. You are quite right in identifying that there is no guarantee that the US Census median family income reflects the Lutheran median family income. The adjustment was added because some critics of the draft argued that it wasn't fair to expect synods in poorer regions of the ELCA to support at the same rate as those in wealthier regions. Ironically, my synod is in one of the poorer regions, and my hunch is that the membership, while perhaps above the median family income in this region, is most likely not in the third standard deviation. I would doubt its even half-way across the second standard deviation. So, I would have been fine without the adjustment.
Yes, I think that we have done something well in this synod. More than ten years ago, Synod Council made a point of visiting congregations and talking about what happens with mission support (i.e., where does the money go). We also set a goal of 15% proportional share from the congregations. Prior to that point, median mission support of congregations was around 8% with a huge standard deviation. A lot of hard work went into making these changes, and the fruit evidenced itself. At the high water mark, support went over 13% and the standard deviation narrowed.
The Blue Ribbon Commission on Mission Support (I don't think that was the exact name, but close enough for ecclesiastical work), however, failed to inspire change across the ELCA. Differences in ecclesiastical ethos militate against sweeping change. For 20 years, the ELCA has talked about stewardship, but I haven't seen the evidence that that talk has accomplished anything. Instead, we have sections of the ELCA in which congregations bring in much greater giving from parishioners than is the case in my synod, yet a much smaller percentage makes its way to the synod (and thence to the Churchwide). Alienation and ecclesiastical ethos are part of that equation. I no longer expect those militating factors to be overcome. Rather asking yet again for everyone to raise their standards--something which has not worked--I am ready to adopt a uniformly lower standard (as my synod would deem it) and go for per capita.
Fundamentally, I would consider per capita more equitable. Repeatedly, in regional and synodical consultations with the churchwide, we have been not to be critical of those synods in the lower ranks of per capita mission support because it is common among them that congregations directly support ministries rather than supporting through the synod budget. While that sounds good at first hearing, deeper analysis reveals that the proportional share system relatively penalizes grant recipient ministries in synods where mission support is the primary conduit. Furthermore, synods in which mission support is the primary conduit end up supporting ministries across the whole church while synods in which direct support is more common end up supporting only regional ministries.
So, my proposal was not intended to work some redistribution of wealth. Rather, it was self-abandonment to localism. Localism is a feature of a good chunk of the church. I don't see that changing. In my synod, because of the dominant ecclesiastical ethos of the region, we need permission to function in the same fashion. Lacking that permission, we will continue to support a broken model for mission support and, as a consequence, cripple our synodical ministries as a matter of loyal support and obedience to the churchwide model of mission support which some synods follow and others don't.
If I were to describe the ELCA as a ship (a venerable image), I would say that it is a Viking long boat (in deference to my Northmen colleagues). The problem with mission support in the ELCA (at the synodical-churchwide interface) is that only half the Vikings are rowing. Requests and pleas that all row haven't done any good. I'm ready to stop rowing. Either we all meet the same standard as articulated in the design of the denom or we change the design to meet the standard which people are willing to meet. What it would mean for my synod is the ability to fund more vigorously mission and ministry.