I suppose that I could try KeePass, but I would need to transfer my 538 items from Password Safe to KeePass to really give it a thorough test.
My 538 items are in 12 top level folders, each folder having up to 5 subfolders. I don't think there is a limit on these numbers.
Regarding plug-ins, I don't know what others I need, as it does what I want it to do, i.e. finding an entry in the database is simple, right clicking on an entry allows me to browse to the URL and/or auto-type the password (if the entry is a web site), or just auto-type the password where the cursor is.
I don't know what else I would want it to do, apart from exporting the database in a format that can be read by other password store programs, such as KeePass. But the last time I tried I couldn't find a program or plug-in to do it. Maybe I'll write one to convert from Password Safe's XML or Plain Text outputs to whatever KeePass uses for import.
If you can think of something that KeePass can do that I've not listed for Password Safe, please comment.