Mh, I think it's difficult to compare rapists who kill their victims and rapists who don't. But one thing I must clearly outpoint: Rape is ALWAYS violent. Cause it's just about might and power, not only about "making love".
I don't say "rape is worse than murder", but I think, rape could be kinda "equal" to murder. Not exactly, but nowadays it's still taken too lightly. In worst case, rape kills the victims inside so that a normal life isn't possible anymore.