How (and when) to switch transfer modes of Cloud Sync Tasks

[vitaprimo]

I'm about to set up a matching sync tasks to sync a directory between FreeNAS and a WebDAV server. FreeNAS is the target for the initial sync, each will only push their changes. The source server, being the only one that has to do work for now, has already begun pushing files, on FreeNAS though, I've been staring for like half an hour, while also looking for someone who has already done this to see how it went--I'm afraid since FreeNAS' side is empty, it'll push mass deletion of files on the source server.

Paying closer attention to the settings it appears I was right on that, the SYNC transfer mode does exactly that. It obvious I have to do initial sync using the COPY transfer mode, but, will it be safe to switch to SYNC once that's done or will there be issues if the files structures aren't exactly the same. The other server is a Synology unit; they mount their volumes right at / and this was exposed to FreeNAS over WedDAV, while FreeNAS on the flipside decided to make WebDAV the one protocol in which it wouldn't expose the whole tree. And then there's symlinks…

These are recovered files that I just finished deduplicating for a month, a little more, it was painful. I don't wish that on anybody. :( Anyway, any guidance would be awesome--a past experience would be better so I know what to expect; while writing this it already did about a third of the copy, for WebDAV that's insanely fast. Thanks guys!