Your problem is not how you configure the software. You need to start with a permissions model which allows the right users to change files and the right users to read files.
First off, FTP is plain bad. Do not use it unless you have absolutely no choice in the matter AND you/your customers will not be disadvantaged by some third party getting access to all your data. That you can install a FTP daemon means that you do have a choice. While there are some very good HTTP based file managers out there, this is only a viable approach if it runs on a different server than content serving, and over HTTPS. Really the only sensible option is SCP/SFTP.
Regardless of which method you choose, the content should never be writeable by the webserver uid - if you need to provide upload functionality then these files should be stored outside the document root and access should be mediated by code to prevent injection. Set the permissions on the base directory to 777, and only modify the contents via the webserver.
If you only ever need a single user account to upload content then the solution is simple - just set umask u=rwx,g=rx,o=rx (i.e. 022)
The link you cited at http://forum.slicehost.com/ describes what one person did - and they start off by admitting they didn't know what to do. The solution they came up with leaves a lot to be desired.