I guess I'll now focus my attention on Net::FTPServer, which I can subclass and modify as needed.
I don't think there's a single good FTP server for Unix. I should stop working on LiveJournal for awhile and work on things like helping the ProFTPd people out.... who else is going to? But will I? Probably not. Everybody's too busy.
Update: Screw helping the ProFTPd people ... Net::FTPServer looks mad cool.