I spent a number of hours yesterday downloading the 400 apps for the first time, but another program demanded an automatic restart of my PC during the install phase. This meant that the downloads that already exist in a previous temp folder are now "ignored" and the files have to be redownloaded thus wasting even more time.
How about setting up a named location %appdata%\temp\PA_Downloads\ which store any and all downloads until they are installed? That way if the process gets interrupted, it can easily be resumed without having to redownload the payloads again.