This reference to discussion on Alfresco WebScript Connector - Testing Question .
Recently we have started to test Alfresco 5.0.1 enterprise edition with manifoldcf 2.2 and Solr 5.3.1. Initially there was a issue with webscript as we could not get alfresco started after applying the indexer webscript. We have opened an issue here  and we have made changes to fix that issue and fork is available here.
According to our tests, with regard to change sets, modification to existing documents and new document additions are detected by manifold and indexed correctly in Solr.Also site filtering works as well.
But document deletions are not detected and consequently deleting docs from alfresco does not delete documents from external solr instance. We are currently looking in to that issue. Any help would be greatly appreciated.