Facing the same dilemma here.  

There are some sites for which I can't download the http version, and vice
versa some sites which can't download https

Then there was a stubborn website which won't download using either http or
https.  I finally put http and https together in the same project but it still
didn't work

I haven't tried that for a normally downloading website.

One thing though: selecting "update" instead of "continue interrupted
download" will redownload everything.

Found that out the hard way after wondering why these downloads are taking
forever....