Somewhere further down this thread there is a suggestion that the issue is selling hosted cloud space. I don't mind buying space to hold pdfs elsewhere (although it raises copyright issues) but I certainly hope that it is not the reason we don't have a solution to the "own folders" (and different computers) issue. Needs fixing.

Yes, this certainly needs to be fixed so that Mendeley on a second computer looks first to see whether there is either a copy of the original folder structure and files or a Mendeley-generated set before it starts downloading everything again. Workarounds shouldn't be necessary.