Sub domains vs Folders

Hi. We have a community site with around 30 k members and more or less 3k hits a day.
Problem we have is we have 4 sites running under one domain. ex.
Site.com/
Site.com/site1/
Site.com/site2/
Site.com/site3/
I wasnt around with the initial setup, now I am left with a mess where the backups file for the site is 32GB and this makes managing. We got hacked and took me littereally hours to get it restored.
Now I am wondering. If I move that sites to a sub domain structure. For Instance…
Sub domains vs Folders

See original post by Janes Oosthuizen