If you've used both FTS in postgres and either ElasticSearch or Solr recently: Objectively, what are some data points when you need to switch over? E.g. more t

If you've used both FTS in postgres and either ElasticSearch or Solr recently: Objectively, what are some data points when you need to switch over? E.g. more than 'x' values to index, index update time, or perhaps features like prefix/substring/phrase search, lack of facets, etc.