I've not read all the nearly 800 posts and hope my suggestions wasn't mentioned before, but did you guys think about creating a button / link to send the pdfs (or zip files) directly to a dropbox account?
It's annoying to hang out on your website, getting logouts, having to log in again, just to still not be able to download the file....
If I would have the option to send it to my dropbox, then I would use it. It doesnt matter how long the queue is or how long your system needs, because when the files are ready and get send to the dropbox, I get them automatically downloaded.
Maybe you could think about that?
