The thread you linked refers to Sitefinity 3, which is an older architecture. Versions from 4 and up use a new architecture, new DLLs.
However, with the new architecture comes a new Layout Editor, that, in my opinion, eliminates the need for nested master pages.
For a video of this in action take a look here: http://www.sitefinity.com/devnet/video-tutorials/pages-management/page-layouts.aspx
You can create a base template using the master page file, then create new templates that use that template as a base, with differnt layouts (Two Column, Three column, etc)
The base template can have the sitefinity widgets, elminiating the need to embed these onto the master file itself.
Hope this is helpful!