Hi,
I think it really comes down to personal preference. For my
P4P I have both the + controller and the regular controller with a large tablet. I honestly use both. The + controller is great for the fast and easy setup. Just open it and go. The other benefit of the + controller is the brightness that I just can't get from any tablet. However a tablet gives me the nice 10" screen, and the ability to load other apps. Generally I really don't need any other apps but it is nice to have Litchi.
So really think if you need that flexibility and want to incur the cost of both a tablet and another controller.