As a relative newbie still, I bought both a year or so ago. While you'll eventually figure out your own rub and sauce, I find that Jeff's rub and sauce get you over the hump so to speak.
They get you over the hump by allowing you to concentrate on the actual smoking process instead of being overwhelmed by the trial and error of building a rub and a sauce. This gets you comfortable with the rest of the process which, for me at least, was key.
Concentrating on getting my prep, cooking and resting process down without worrying about what the rub and the sauce is going to taste like when things are done has definitely made me better. When you know the sauce and rub are "on point", you just have to cook it low and slow.
It's worth the money in my opinion.