I am confused as to the need for the NALC when most congregations that have already left went to the LCMC. What is the difference?
Lightman can probably give a better answer, but I would say that NALC would be more on the evangelical catholic side whereas LCMC would appeal more to the congregationalists. I think it has to do mostly with church polity and, to some extent, worship style.
NALC will also organize itself as a real church body. LCMC is a coalition of independent congregations.
LCMC welcomes evangelical catholic congregations, by the way, but real evangelical catholicism is not congregational. That is one reason why at least some congregations are waiting for NALC before they leave the ELCA.