Another thing that strikes me is that if Boromir wasn't going to be killed anyway, you'd have to murder him. He is a constant source of negativity yet so up himself he is in danger of turning inside out. Had he survived I don't know how many companions he woudl have got to go to Minas Tirith. The film Boromir is more sympathetic in some ways (and that is from one of the few red-blooded women who isn't keen of Sean Bean)