Very well I would say (20gb and counting). More importantly: Zotero is the only one that does Web scraping correctly. If you are looking at a paywalled article, it will capture your DOM from the browser, so you get what you are looking at. DevonThink and many others choke at paywalled content because they try to access the content independently.

Last but not least: thanks to the developers for the latest updates that bring zotero to a more modern experience. The iOS app specifically is awesome!

You can use them both together! Just have Zotero save your PDFs to a directory that DEVONthink will index. That way, you can use the right tool for the job. For inserting citation into documents, the work processor plug-ins that Zotero offers are really fantastic. Similarly, for academic papers, the web clipper that Zotero has is much better suited to those particular types of documents than the more general purpose one included with DEVONthink.