Good approach, with one flaw
In general, it does well what it promises and works very fast on my library of 20k+ photos.
However, it doesn’t seem to consider album memberships of photos at all. If you use automatic clean-up, it might delete the duplicate of a photo that is part of an album or another project. It requires manual work to fix that, which is a lot of effort if you have a lot of duplicates in our library, unfortunately.
vsp about
Duplicate Cleaner For iPhoto