When would you use Modules and when you would stick to Controllers?
Same as you. For major sections of my website like the front-end, admin section, members section, etc...
Whats your rule to decide Module or not Module ?
Is it part of the main site or its own little world just related to the front end? Especially in regards to design. How do you manage a couple of modules some using the same layout?
What are the cons AND pros of my colleague's setup in your point of view?
My God the maintenance. All these folders for nothing at all. Why have your about page and contact page in two different file structures? Also where does he put admin and members if he uses modules for simple pages?
What are the cons AND pros of my setup in your point of view?
Really the opposite of the above. Easy to understand and coherant structure.
Its worth it to add its the way the zend team intended us to use it link
Another thing to think about is what will your urls look like.
myapp.com/contact
myapp.com/about
myapp.com/members/profile
myapp.com/members/profile/edit
myapp.com/members/mail
This is one easy way to help organise what will go in modules or controllers.