There are some aspects that SF still do a lot better than the competition on. Nobody is even close to competing with the speed and breadth of their mirrors.
I've never hand bandwidth trouble with either github or google code. With SF I get an arcane 2001-Era dialog where I choose from 12 options that don't tell me anything - just imagine what this is like for an normal end user.
In any case, bandwith and storage cost falls faster than executable sizes grow, so in a few years this will be a non-issue for competitors even if you assume that it is an issue at the moment.
Edit: Githubs download expierience:
https://github.com/mirrors/linux-2.6, click on downloads in upper left corner, click 3.0-rc1, downloading 115mb and my bandwidth is saturated at 2MB/s.
