I find the Reading List plugin helps a lot with this:
I have a custom column, tag style text.
I keep a list for each device, which adds/removes an appropriate tag in the custom column.
After I finish uploading books to a device I clear the list (in the plugin menu 'Edit list', select all, delete), then search ondevice:true, select all, and repopulate the list (in the plugin menu 'Add to list').
Thus my custom column contains a tag-style list of all the devices a given book is on.
I tried to convince kiwidude to automate the list repopulation but he didn't bite

, it's still quick 'n easy.
(I also keep lists of what to add/remove from the device, which tasks Reading List does do automatically when I connect -- which is a real delight. But that's beyond the scope of Iskariot's original question.)