> > Should have said: What is the penalty when
> > restarting the run.
> 
> It asks the server have the existing files changed.
> Depends on round trip time, about 3 files/second,
> independent on file size. Dynamically created files
> are always new and redownloaded.

This sounds as what I understood for the 
 $httrack --update
run. 

Is a restart in  a directory with a hts-cache equivalent to the run with
--update, then?
and if yes, a related question:

Does a restart when you change options/ filters also work as an update?
ta
Krys