I'm undecided. Ben seemed to be threatened by Locke's knowledge of Eloise, and that's why he killed him.. he thought Locke knew too much maybe and would get in Ben's way, or change Ben's plan. So, he kills Locke. At that point I thought, he knows he's important but he just wants to get rid of him until they're back to the island so he won't disrupt any of Ben's plans. But then he tells him he'll miss him, and I took that literally, because he wasn't speaking to anyone, just himself. So, then it makes me think that he thinks Locke is really dead.
See you in another life!