I'm with you on the port-like system ! Here are the pros:

• Everyone can see the recipe to build <package>
  
• It is easier to recompile a software according to your needs
  
• If a package don't build anymore, anyone can submit a new "recipe" ...
  
• ... and mail this recipe to the maintainer of this package
  
• Automation of the building system is easy
  
• Anyone could share pre-compiled packages with the community
  
• Shell scripts (for the recipes) are easier to write than Makefiles
  
• That'd be cool to have OUR package list :)
  
• Could make rollback easier if every port is git-versionned
  

Let's go for the cons:

• Users need to compile their softwares (if nobody built 'em before)
  
• Community driven package system (like AUR / Contrib)
  
• Create a directory tree on the user's system
  
• Rolling-release is MANDATORY