If you want to help, maybe see if there is a way to make it work with torrents? (Specifically, gameupdates.org torrents).
See, then we wouldn't have to really worry about bandwidth. I know Azureus is a java based bittorrent client that is open source.
But, since I'm not a coder, maybe this is all more complex than is possible to code easily or it isn't efficient.

I wish, though. I really wish.

gameupdates.org speeds were blazing fast when I used them. I'm uploading FSO + mods to GU once FSPort releases the next version, but I'd rather there be a way to automatically download specific torrents containing mods, which could then be updated as needed and the installer would get the latest one. (I know GU supports replacing torrents with new versions, as well as some sort of auto-download script. Also, the GU coding is open source.)