For years I've migrated my 20k images between Aperture, Lightroom, Capture One , Photo Supreme, Bridge, Media Pro and others several times as new versions were released. Each and every time I had to spend days reworking the keywords and deleting duplicates. I wished to only have a hierarchical list, although I do wonder if that is a good choice. I'm currently back with Lightroom. They all had their problems, but I think Media Pro was the best - until it was discontinued with no hope for a 64bit version.
I'm retired now, so I do have the time for this, but I'm fed up to the teeth with false promises, buggy software and not being able to do what I need. You see I've scanned every photo I have going back to before my parents were born, trying my best to figure out the WHO, WHERE & WHEN. The process is almost forensic, because those that could have helped are either too young to remember or dead.
It's a case of trying to guess someone's age, trying to recognise a location with the help of Google's satellite imagery, Wikipedia and pot-luck. It might help if I could present all the photos I think I've dated on some kind of a linear time line, so I could slot in others where appropriate. Almost all of the dates I've assigned are no more than a sloppy guess, but current applications don't implement fuzzy dates.
I'm ranting and frustrated with my progress and wish I'd never started, but I would like to finish this project before I die. Then I won't be needing to post inappropriate contributions to forums like this. Sorry.