I believe we discussed this over Project Week thinking it is not really about the dissemination mechanism (custom packages vs extensions), but about having a start-to-end software solution that serves a very specific research community. These communities can be either methodological (i.e. salt, dmri) or clinical (i.e. IGT, CIP).
The problem here is that we might be getting a bit tangled on the syntax/branding of what we are trying to provide more presence to. Maybe “SlicerDistributions” refers too much to the dissemination vehicle. I believe it will benefit everybody to present these specialized solutions within Slicer to our user-base 1) because it might attract specialized researchers to the Slicer community 2) because it showcases the real power of Slicer to be customized to a number of different applications.