The recommendation is to get a version with an unlimited number of users, because the development list for the product is extensive and what would be worse than to find out tomorrow that you have a lot of great features, but can't use them (because you simply don't have new logins for the roll-out to customers).

Unlike others here, the interest in WebDAV is low - when I look at an SFTP tool, the focus is on sftp :) But other things on the roadmap I find very interesting and from then I would also use the product productively, currently I rather test for myself.

What it can do at the moment are the core functions you expect, a few more small improvements in user management and then it's a great solution.