[evunveot]

I've never used it professionally, but dotCMS is a Java- and Elasticsearch-based CMS that has very impressive multisite features [1]. From what I can tell, a lot of its capabilities stem from a design that treats absolutely everything (data, content, static assets, "themes") as a node in a virtual filesystem, or rather a filesystem-per-site, so everyday filesystem operations cover a lot of use cases. I believe you can even manipulate your site(s) via WebDAV to some extent, e.g. to develop a theme in your IDE of choice while saving directly to the site or, more realistically, saving to a private staging copy of the site that lives on the same server, which you can then copy into production from within the dotCMS admin.

I gave some consideration recently to adopting dotCMS for client work to replace an in-house PHP CMS, but although Java-the-language isn't particularly intimidating and dotCMS itself looks fairly self-contained and straightforward to deploy -- Elasticsearch is embedded rather than requiring separate setup, for example -- it's still tied up in the Java ecosystem (OSGi, maven, XML configuration) so there's a lot to get used to for someone approaching it from outside that realm.

[1] http://dotcms.com/#anchor1