Mac Keychains in sync: an other one to save web passwords?

I use Dropbox to sync my keychains. I were syncing the default login.keychain but due to some issues (password ask at login, different tokens for apps which store it in the keychain, files conflicts between Macs, etc), I tried to use another keychain named passwords.keychain to save my web passwords and use the default login.keychain for the rest.

But Keychain Access uses a default keychain, then I can't specify to save web passwords to passwords.keychain… and that's simply doesn't work on Chrome/Safari/Firefox(with plugin) with autocompletion.

An idea? Do I need to use a service like 1Password? Can't Dropbox solve that gratis?

(oh and yes, I don't want to use that iCloud solution…)