I'm relatively new to PHP and have been writing a project using what I believe is a fairly basic file architecture - all files and sub-folders within one main site folder accessed separately. Within the project, I've been using the Zend Framework as more of a library than an actual framework. I'm happy with Zend and using it like this makes things very easy. However, I have recently been starting to dread the maintenance and expansion that may be required with the project (something I should have thought about before, I know). I have been doing a bit of research and looking into using the Zend MVC rather than the basic structure as it appears this would help to remedy that fear. However, it would mean a lot of backtracking in the project (not a huge deal, just a little frustrating).
What I'm wondering is if there are any other reasons why I should take the time to switch away from the basic structure over to an MVC architecture, or if there are any other file structures I should be considering?