I am a little unclear on what problem we are trying to solve.
Is the issue with the download files being too big or that the server serving them is not transferring them fast enough? I would be surprised at the latter as our server has always had a pretty good connection to the net.
For former, and based on the discussion at Save bandwidth and money by better compressing the audio, I am going to investigate shrinking the files this week.
@sil we may want to automate the compression as part of our publishing script.