stock is cutpile I believe not much give to it, so plush will add more comfort. I myself when the time comes will be doing the plush with mass backing. you could also get samples of thier colors and paddings to get a better idea.
good comparison photo
war if the metal on your floor is muddy, then no carpet backing will save you, also its called floor mats and a whoopin for those who walk into a car like that!