Yes, in MacFamilyTree 7 and 8 you can also store your database in a custom location. That way you can also define a Dropbox folder as storage location.However, if you plan to collaborate with others on the same database, please make sure to create regular backups, as concurrently editing the database within the Dropbox folder can destroy it.
Select Dropbox as storage location
Go to the top menu bar and select “MacFamilyTree” -> “Preferences” to open the preferences. Go to the “Databases” tab to define a custom storage location.