Interesting feedback, thanks for taking the time! I hadnt tried with over 500 honestly, mainly because it takes too long (until ive got good background processing in place so you can switch apps whiles its doing the work ), so thats a great observation.

I like the idea of annotating the photos within a group, updating the metadata so you could reference them easily in the future - I shall investigate. But yeah, everyones has a different relationship with their camera rolls, this initial app version is primarily focused on people who have duplicates/vacation photo cleanup/bloat etc todo, but I'll definitely look into other avenues of functionality it could offer.