Which symfony-based CMS is the most extensible?

I'm looking for a symfony-based CMS, and I have heard about Diem and Apostrophe, but none of them offers all of the features I am searching for.

In your opinion, which of these CMS' is the most easy to extend? Do you know any other Symfony-based CMS I would want to consider?

EDIT : By 'to extend' I mea开发者_运维技巧n adding probably unsupported features, like Pdf rendering, adding menu from another sf application, content creation through web services... and all sort of special stuff my client would want.

Both Diem and Apostrophe will allow you to extend quite easily.

It is just a matter of selecting the base that best suits you.

Apostrophe already has many of those features. Check out Apostrophe engines.