Hrrmmm....well my 2010 LLT doesn't seem to have a bad delay. I can't say that it is instantaneous or anything (off idle), but if I give it a good amount of the go juice it seems to take off quick enough that I don't notice anyting abnormal.
Of course I can't speak of the LFX.
Going to be hard to determine this without you trying another owners V6 or maybe even posting a video.
5th gen IS SOLD! 6th gen built 10/14!!! Can't wait!!