I would say that there is still some delay when suddenly mashing the pedal when already moving. When mashing the pedal from a stop, the tires start to spin and the traction control takes over.
I can tell you that the response after the moment delay will put you back into the seat.
I would think that instantaneous response would be extremely harsh. I would not modify this. On my gas 6.0 in my Express, when you floor it the RPMS jump and downshift quickly, but I feel that there is no more acceleration than the new Duramax.