So I have a D300 Body with no lens on the way. I original intended to get the 18-200 DX VR lens, but after the release of the D700 I've been thinking about lenses in terms of an investment. I'm fairly certain that this camera is going to be the last camera I buy that will not be Full-Frame. From an investment standpoint I feel like I should buy a non-dx lens to save me some money down the road. Is this a wise idea?