I am messaging you because I wanted to ask a question outside of public, just in case this hasn't been thought of.
If the bookmark files is encrypted and the key is built into Yummy, I understand the Bookmark Files are encrypted. But as a hypothetically, if I did the following I believe I could get the passwords:
1. Get the Yummy Bookmark Files
2. Install Yummy on the new computer and restore Bookmarks
2. Change server settings of the bookmarks (but leave the server password) to a local unencrypted communication (like local ftp server)
3. Run a packet analyzer and tell yummy to connect
4. Get passwords.
Thank you for your time.
I replied to your message this morning… sorry, I rarely get forum messages : people usually use email

As I pointed out in my reply, if someone can get access to your Yummy FTP Bookmarks from your computer then they can get access to anything else including the Keychain file, email accounts, bank details, etc etc… they could just install Yummy on their Mac and connect : no need for the convoluted packet sniffing method.
If you're hyper sensitive about security you should be using SFTP and a keyfile access, not FTP (which sends passwords in clear text by the way) and not passwords.
For DropBox syncing purposes you can leave your passwords in the Keychain if you prefer. It just means that passwords won't be automatically synced.