Having purchased my 3-D two months ago, and now after about a dozen uses, I'm glad that I paid extra for the built-in PID. While SI is new to me, I'm no newbie to smoking and grilling meat. It's one of my favorite hobbies. The 3-D has proven to be able to keep it's heat exactly where you want it, and that is what I've enjoyed the most. Cooking to your desired internal temp is icing on the cake. If the PID should fail, I'll use my WSM and work with my lump charcoal as I have for many years. In fact, I'll continue to use my WSM, as it produces wonderful smoked meat. It's just not as easy as The 3-D and definitely no fun in freezing weather. That's what sold me on the 3-D, is ease of use. Now that I've seen it in action, I've no complaints. Brining two loins as I type, which I'll smoke this afternoon. For those still sitting on the fence, you probably can't go wrong either way, but I don't believe that you'll be reading too many regrets from those that bit the bullet and paid a little extra for the 3-D. Happy Smoking!