No, you shouldn't cut off a Sumatra's comb. The breed standard calls for the comb to be a purplish-black, or mulberry color. But you see red ones like yours all the time.
Found the pics of my Bantam Black Sumatras, Celeborn and Galadriel. I got these from a breeder in Florida. One an auction on eggbid for a 3 month old started pair. I loved them.
And I apologize for the grainy pics. These are scanned copies, not the originals. Somehow I lost them...
No, Kurt, the mottleds carry a recessive gene for mottling that the splash do not possess. Aslo, in splash, its just random splotches of color. In mottled, there is just the white tips.