I have almost completed a PHP project, using MVC, jQuery and Ajax. It is pure PHP project. I don\'t use any frameworks in the code right know. I would like to change that.
I actually recently converted a MVC pattern website I had built from the ground up into Yii. It did take some time to set it all up but in all honesty it was well worth it. I was able to throw away a lot of code because there were already Yii extensions doing what I needed. I would also suggest that you keep your database because you can create the controllers and Models using Gii which will save you a ton of time.