As a Rottweiler owner and lover of the breed in general I urge you to go with a name other then something like Demon, Mauler, Killer. It is hard enough already trying to uphold the good name of Rottweilers with all the idiot owners out there who raise their dog to be mean. Names like Demon, Mauler, Killer and what not further push the stereotype of an evil breed. That is not publicity that Rottweilers need as all the dog fighting, uneducated, low life morons out there ruining the name of Rottweilers are more then taking care of running the breeds name into the ground already.
Flame all you want, but owning a Rottweiler carries with it a responsibility unlike many other breeds. It is our job as owners to make the dogs life as good as possible. In addition with a Rottweiler you are either helping the breed name by good raising or ruining the breeds name by giving the impression of a mean and evil breed. A Rottweiler does not need to be called Killer to make him protect your family and household.