I'll take this one Parker

In basic terms.... a 1264dr loads up and flexes so much from tip to butt, the blank bends inside the unflexible carbon handles and forces the grips to shift off the blank. I recall Parker's rod blank shifting all the way to the edge of the carbon handle and touching it...crushing the grommet seal at the head of the grip...not good. Over time I would bet that the grips would fail due to the inflexibility of the carbon fiber.
A cork handle will flex with the blank much better when you have the rod loaded up on a DR.

I think the carbon fiber is ideal for the very end section, say last 8-10 inches, of a DR rod that spends it's life fishing inside the rod holder getting beat up.