Local syncs are surely faster, especially if the local sync store is on the same machine or a connected drive. WiFi connected drives will be a bit slower because, well… Wifi 
but an Ethernet connection would likely be fairly fast (and far more stable than Wifi… because, well Wifi 
)
Regarding WebDAV, yes there could be some inherent security risks trying to access it off network. That would be up to the individual / manufacturer to try and work through.
Thanks for the nice comments and advocacy. We really appreciate it!