Cleaning up my hard drive...
I would look at it another way. You need to identify which pictures you want to keep. Tag those with say 2 stars, maybe's with 1 star and then delete whats left. This should be easier as you have already processed many files. You may see the wisdom of in future linking the raw file to the processed file with some common index.
Multiple image views will help speed up this process, but only you can go through your images. Good luck and make it a fun thing.
Flickr D800 gallery
FlickR Nikon1 V1 gallery
|Blue and yellow in water by fireplace33|
from Ink and water
|Kylmä joki kopio by Kaappo|
from Shutter speed 1/25 or slower
|WR_2.8_13 copy copy by photoprof|