Bespoke CMS or 3rd Party?
Sounds like Symfony would be just what you're looking for - with the recent Symfony 2 release, it's also very easy and convenient to integrate additional libraries like Zend, so you can have the best of both worlds for any custom components.
That said, the studio I work for run all our CMS work as Zend apps, so we can fine tune the content management process as needed etc.
I am planning a side project and I want to know your experiences with CMS builds. The project is a fairly straightforward CMS with no e-commerce functionality needed. I know I can build something like this using Zend Framework quite simply. As it is a side project I don't want to spending time doing the tedious stuff like building and styling the dashboard and I want to focus on doing the bits that are bespoke and important. So I am tempted to use a 3rd party CMS like Symphony or even going in the direction of TurboGears or Django as I have been looking for an excuse to get on with a Python build for ages. 
My question is it best to 're-invent the wheel' using Zend Framework which could add an unnecessary overhead to development time, or go with the untried and untested (by me) and cut out the backend design. I like the second option but I am worried that the time taken learning a new platform could also add an unnecessary overhead. Both choices seem to have upsides and downsides.
Any advice, suggestions or personal experiences that can help me here?