Well I would think it would depend on who initiated the update as it can download or upload.

Think it is designed to allow the client to be able to run other network applications and stuff and not steal all the clients bandwidth not really designed to do complete network throttling. If the client isn't doing anything else it will attempt to download as fast as it can, in which case if it was a drain on the network you'd still need to use the router to control the bandwidth of the client in regards to overall usage on the link.

That's my take on it and may not be accurate without reading all the docs and participating in the newsgroups about it.