Originally Posted by NeilH
Now that you mention it. It seemed like once I got past the 'stall' the pit reading was reading the same for the most part as the guru. That was about nine hours into the cook. I had them both about 3" to the side of the meat. The maverick was in the clip they provide (metal to metal) and the guru was clipped to a wooden clothes pin. The maverick pit probe was on top of the grate and the guru was on the bottom. Still don't understand a 20 degree difference in the pit probes but like you, I tend to trust the guru.
It could be as simple as the grate was exchanging temperatures with the meat sitting on it (heat is exchanged to the meat and the grate is being cooled by the meat) where the clothespin was allowing the guru to read the ambient air temperature being it was not touching the metal grate itself.