Your missing the point that the ACT is not actually as hot as the sensor is reading due to the heat soak, so in turn retarding the ignition as if the ACT is that high, so taking alot of power away, which is un needed.

That is indeed completely correct, (well other than sometimes the actual temp may be higher than the ACT sees not lower) I havent missed that point at all, thats why moving the sensor to somewhere with a different amount of heat soak to its current position would potentially need a remap of the relevant temperature correction values to ensure it still keeps you the number of degrees from Det you wish to be in all circumstances (or as close as possible)