Asking yourself how your characters would react/what would they do or say when push comes to shove is something I would highly recommend. It's a good test for yourself as to how well you do know your characters (or not as the case might be!).
My favourite example of an honourable character under duress is probably Sam from Lord of the Rings. He has everything thrown at him and yet is still the basic and decent guy he was at the start of the story. I love his absolute loyalty to Frodo. And that loyalty is tested.
So do your characters pass the test of being strong enough to be in your story? Ultimately I think that is the question you should be able to answer positively for all your characters. (Even weak characters can have a useful role to play but have got to add to the story in some way). All characters do have to justify their existence.