When Miles said this, I couldn't help but think that the freighties, like the Others are underestimating the losties resolve. Once again the losties are seemingly outnumbered by technologically superior enemies. Apparently the freighties are unaware that two days previous the losties won a war against the others and destroyed their society. Look at whats happened to team freightie in their brief stay on the island. The one who was supposed to protect them gets knifed in the back, two are held prisoner(I'm referring to Charlotte and Miles), and they're outsmarted in a prisoner exchange. I know Locke was the one who knifed Naomi but it's looking like on the basis of the flashforwards that it was the right move, and Locke is a lostie and though it is debatable, he absolutely believes it when he says, All I ever did was act in the best interests of us all.
It seemed incredibly arrogant for Miles to say that and stupid really, he's a prisoner and the deal he made with Ben concerns him getting out and taking care of Charlotte whatever that means. He may have some brilliant escape plan but considering he walked willing into a trap he doesn't seem like the type who could escape.

I'm glad you brought this up. I thought this was significant too. The way Miles said "Don't treat me like I'm one of them" made me think that he and Ben know something big that the survivors don't. Saying that in front of them seems like Miles thinks the losties are extremely ignorant about one big point . . . just not sure what it is. Maybe he was just implying that he knows who Ben really is and that he has access to the outside world and millions of $$$.

I don't think Miles was suggesting that the losties are powerless or inept, he was saying that he has more knowledge and understanding of Ben than they do, and so he shouldn't try to play him like he has been with the losties. Although the losties have managed to take them prisoner, they ultimately don't actually know anything about Ben or the Others or their agenda.

I think that Miles looks at everybody with derision, so his reference to the Losties was just in character for him. But that line was also intended to let us viewers know that there's a bigger game being played than the Losties (or us viewers) realize. Ben and Miles both know about that game and are on opposing sides, and it's for us to watch for the clues and figure it all out.

(BTW, to make it harder for us to figure out, I think the writers have made the "game" to be three-sided rather than two-sided, but that's another thread...)