Exactly, so with an IC that works below 100% efficiency there would be a measurable (but small) Temp Differance in the intake manifold. 1.25 F in your example.
Will i notice ? i bet no, but Clearly its worth the $3.50 in parts
it sure did bug me that on a 65ish day my filter felt over 100 though. (wild guess, maybe Nick has a better idea)
FYI i have about a 12 X 24 ish sized piece of sheet metal left over if anyone needs it for , well who knows what