Tim,
As folks know, I'm a big fan of the Auber PID. Do you have to have it to make great Q? No! The stock analog controller does fine, and I've smoked a lot of meat with it. The temp swings are part of it, but it will "average out" to your desired set temp. If you're happy with the results from the stock controller, and don't desire a higher level of control and accuracy, keep it as is.
But...if you are like a lot of us, who like a degree of control you can't get with the stock controller, then I highly recommend the Auber. To me, it takes the Smokin-It from being a great smoker to being a phenomenal smoker! Here's what I really like about the Auber:
1. It gives accuracy of set temp within 1-2°. No more swings!
2. You can set 6 separate "steps," so customization (and automation) of your cooking profile is super easy. I really like this when smoking things like Canadian bacon, where I change the smoking temp 3 times during the cook.
3. I can go higher than 250. I don't use it that often, but it sure is nice when I want to! Having options is good.
I would like to present you with "cons" to the Auber, but I really can't. In my world, there is no downside, or dislikes, about the Auber! It works, and gives me the control I desire, and options for temperatures that the stock controller can't.
Hope this helps!