$lwpmechua->show_progress( 1 );

Wow. There is even WWW::Mechanize::Plugin::Retry which probably can be hacked to automatically continue partial downloads, so Mechanize eventually could replace wget.

While I have to admit that I didn't remember about show_progress, the progress bar of wget shows the percentage and ETA and the -c option automagically continues a broken download which doesn't look like a simple task in Mechanize.