The advertisement should be loaded from XConsoles servers IMO, this would reduce bandwidth on the JRunner update/file server.
Anyway, my server(s) are more than capable to be primary or mirror host and I have no problem doing it as I pay for the server hosting regardless.
What I would do is setup a separate VM just for this along with domain's for direct file download along with the JRunner update/file downloading etc. I believe everything is done via HTTP so web server, FTP, and some storage and it's good to go.