Matthew Pianalto has been posting some interesting work on integrity lately (here and here). I've also been reading J.M. Coetzee's Summertime. On p. 63 a character in the novel says that, "Principles are the stuff of comedy. Comedy is what you get when principles bump into reality."
Pianalto's example (originally from Peter Winch, who got it from a film based on a book) of a pacifist who kills someone to prevent an even worse crime being committed shows that the result of such bumping can also be tragedy.
p.s. On p. 94 there's an exchange about vegetarianism and personal preferences or whims that echoes some thoughts found here.
Some old thoughts of mine on integrity are here.