> Update does not start from scratch (except if the mirror 
> is canceled very early.) Update asks the server has this 
> file changed and downloads it only if it has. This is 
> quick (5 files/sec or better.)

For dynamic (PHP or ASP driven sites) a  conditional GET request should not
only be futile but could actually slow down the download as it means more work
for the server (as it has to check the time stamp of each requested page on
the server first, and in the end has to deliver it anyway as for dynamic pages
the time stamp would normally be 'now').

Thomas