Tom, just a quick nickel's worth of 2ยข...
You won't get "better" food from a D model, or added Auber standalone PID. What you will get is consistency, accuracy, and options. Consistency in temp means more predictable times, and less chance of ruining something that can't stand high temps, even temporarily, like fish and jerky. Accuracy....see "consistency," above. Options.... Great to have the ability to set different temps and triggers for more complicated smoking profiles, like for bacon, hams, etc. Also great to have it automatically throttle-down for a long "hold" at 140, while waiting for dinner!
You'll never make better food than you will in the standard model, but you'll be more "in control" with PID control!