I like Kanba a lot, although I didn't until episode 5. I think episode 5 gave Kanba the human aspect I needed to feel for his character.
Kanba is arrogant, a play boy, and has probably hurt many girls but I think he DOES care about protecting his family (not just Himari).
As for the whole incest angle well obviously I feel it is wrong to list after your sister but I think it's more of an innocent infatuation and maybe Kanba letting go of Himari is something he will need to do to develop, but who knows.
I do think part of the reason he hurts those girls is because they don't live up to his sister.
However going back to protecting his family: There is the obvious going after the hat scene but then there is also that shady business he is involved in to let them keep their house.
Why I say he cares about Shouma too is he doesn't let Shouma know about what he is involved in. There is also one line in episode 2 or 3 where he tells Shouma to keep his innocence (or something to that effect).
And in episode 10
So yeah Kanba is certainly flawed but human all the same. It's actually the same reason I like Ringo.