For mailing list participants on solr-user who aren't subscribed to the dev list: I've created a JIRA issue to discuss adding a Solr configuration REST API: <https://issues.apache.org/jira/browse/SOLR-5200>.
I'm interested in feedback of any kind on this proposal, preferably on the above-linked JIRA issue, but here on the solr-user mailing list would also work. There are lots of details, so I don't expect quick resolution, but any input about rationale or use cases for inclusion or exclusion of configuration item runtime modifiability would be very useful. Thanks, Steve