How to filter / find referenced photos by where they are located

Question

Ok guys, I have been going round the bend with this one.... I've been through all of the Filter options in Aperture 3.4.3 several times over the last week trying to find for some way to get Aperture to only show referenced photos that are located on a particular external hard drive (EXT1) / within a particular sub-folder.
In addition to some Originals/Masters being located on EXT1 I also have some referenced photos located on my start-up volume (OSX).
The desired function: I would like to move all of the photos (and video files) that Aperture is referencing (along with the existing folder structure) from within /EXT1/Photos/ to another folder (either also on EXT1 or maybe on to another drive (EXT2), it doesn't really matter where).
Why do I want to do this? I want to check whether there are any 'lost' files that shouldn't be inside /EXT1/Photos/ that Aperture is for some reason not referencing. If I move the files that Aperture is referecing away from their current location then the things that are left over would either need importing into Aperture, or moved eslewhere, or maybe even deleted. Some such files might have been put there by other applications, or by me accidentally, or more likely that Versions of them have been deleted from the Aperture library but the Orignals/Masters were not moved to the system Trash...
I've gone through 5 pages of google results, trying all of the keywords that I think might be relevant, searched many posts in macrumours forums as well as here, but I can't find an answer to what I thought would have been a simple question.
Under File > Locate Referenced Files Aperture can tell me which files are located on each Volume, but from here there is nothing that can be done with the results :-( being able to search my Volume and file path would be very useful to me.
If I've missed something obvious then sorry, but I've gone cross eyed with lack of sleep tonight I thought I'd throw the question out there in case someone knows whether this is type or search criteria is not possible, or if I'm just missing something obvious!
Thanks in advance,
Adam

Answer 1

My next question, which I can post a new topic for if it's suggested, is "can you safely delete the RAW file in a previously imported RAW + JPEG pair?". I did some research into this a few weeks ago but didn't uncover a proper way of doing this, but someone suggested that you can simply just set the JPEG to be the Original/Master within Aperture and then delete the RAW file within Finder.
That is a cumbersome workaround. I cannot really recommend it - I tried it myself. Aperture will complain over and over again about the missing RAW files and even repairing the library will ot fix it. The safer way to remove the raw files from the pair would be to export the jpegs as master and to reimport them, then to delete the older imported versions after lifting and stamping any edits you may have done already.
Aperture's built-in feature to keep only raw for selected images is to allow to import only the jpegs first, browse the images, and than add the raw later for the images that you want to have at a better resolution.
From the Aperture Manual:
If you import only the JPEG files and then later decide you want to download the RAW files as well, you can have Aperture identify and import the RAW files that match the JPEG files in your Aperture library.
To import the RAW files that match the JPEG files in your Aperture library 
Choose “Matching RAW files” from the Import pop-up menu.The Include pop-up menu appears below the Import pop-up menu.
Do one of the following:
To import all matching RAW files regardless of rating: Choose “All matching files” from the Include pop-up menu.
To import all RAW files matching JPEG files that are unrated or better: Choose “Unrated or better” from the Include pop-up menu.
To import all RAW files that match the current rating: Choose “Current filter” from the Include pop-up menu.
Regards
Léonie