Correct me (please) if this is wrong, but keeping the IAT somewhat close to its original location keeps the IAT readings accurate. I see no benefit to installing the IAT any farther upstream- first I am inclined to believe the IAT reading would have to be drastically different to see any performance gain and second, giving accurate values on the incoming air charge temperature would allow the computer to properly do its job, providing optimal performance.
In my eyes, and feel free to offer up your own theories, moving your IAT farther upstream is on par with using one of the gimmick IAT simulator "chips" from eBay. The ONLY time this may not be the case is if indeed you were pulling air that was much much cooler through your intake piping, and you actually had the piping insulated heavily enough so that that air'* temp changed very little on its journey to the throttle body. And we all are aware of how high underhood temps can be on our cars.