So does this new Install Manager work good if you don't use DS on your little internet device, but on a completely separate, detached workstation?
Yes, with caveats.
You can download to one system and copy the downloaded files to another. If you install IM on the stand-alone system you can use it to install the content you downloaded.
BUT - to keep from seeing the same items in the 'Available for Download' list (and to get notifications of updates for items you've downloaded) you need to "install" the files on your little internet device. Set up a dummy directory, install to it (tick the box for 'delete installer once installed') - and then delete everything from the dummy directory.
The other caveat would be if your 'little internet device' can't run IM - you need both the zip file and a customer manifest file for each item; IM gets them both but I don't think the manifest files are showing up in 'My Downloadable Products' - nope, just checked, not there.
I'm downloading to a laptop and installing on a dual quad-core tower, so I know that process works.