WebDAV goes over HTTP in the same way as a POST does, so I wouldn't expect it to be any more reliable than a normal web form upload. However, I'd love to be told I'm wrong :-)
I think it completely depends on the client implementation, as the underlying protocols are stateless. I just assumed that WebDAV clients would be more optimized for long transfer times than browsers, which normally specialize in GETTING data from the web, not posting (large) data. We haven't tested this in any way, though. And as I said, up to more than 100 MB we had no problems (apart from having to wait) with POST uploads (using Internet Explorer 5.x against a Linux Zope server). BTW: For uploads that large, a lot of RAM on the server might be needed. I am not sure whether Zope tries to receive and store the file in one bit, but if it does, you need enough memory to hold the whole thing if you don't want to put your server into "swap mode" ... Of course there are ways of doing the file handling on the server in a streaming way ... Joachim