So, for the past couple years, I've been using systems like WordPress and now Drupal to construct client websites. Most of the development has been front-end with themes and simple widgets (or blocks in Drupal). Don't get me wrong, I love using those systems, but now I want to move on to something greater that I can truly say "I built that". A lot of people here seem to have that aspiration. The only problem is (and probably my biggest pitfall) is that I'm a perfectionist. I build websites that are pixel perfect, and when building my own system, I want it to be as modular as the great ones like WP and Drupal. This is becoming extraordinarily difficult as I am not a PHP expert, but I also want to build a system that will work on multiple client sites.
The question is, should I use a framework?
As mentioned above, I am no PHP expert and want a modular system I can call my own. Does it inhibit one's ability to learn PHP when using a framework like Zend or CodeIgnighter? What are the advantages and disadvantages to using a PHP framework to build applications?