My question on the subject would be: If I want to play with a controller, will I be forced to play with the PS3 UI or if I can choose to play with a controller on the Keyboard/Mouse UI (like we did in 2.0)???

Why? Because, from what I read, the PS3 UI will not offer a great deal of customization (fixed UI) and since I like to re-organize my UI to my liking, the PS3 UI doesn't really appeal to me.