You need to evaluate your plans for your truck.. Only after you do that can you make a wise decision on the tuner.. A tuner isn't a set and forget type of thing, usually.. It takes refinement of the data tables to really reach the final net gain. If you plan on sticking with a stock setup, I would forgo a chip OR a tuner... If you plan on a supercharger, turbo, or NOS(which it seems you will) and want to eek the most HP and ET out of your vehicle then a chip or tuner is probably a wise choice.. BUT you need to also evaluate your abiliity and knowledge to try to tune your truck.. If you have very little knowledge of where to go with your tune, get a chip and leave it to the professionals.. If you want to learn about YOUR truck, and what makes it run better than I highly recommend a tuner(which is the reason I have one, a quest for knowledge)
Just evaluate yourself, and your plans, that will answer your question whether or not to get a tuner..