Being somewhat ignorant as to the differences between lenses, why would an 16-85 with the same aperture as my current lens do a better job than the same speed lens in 18-200?
Are the optics in the 16-85 markedly better than the optics in my current kit lens?
Because at the wide end (and only at the wide end) it is sharper in the corners than the 18-55. An improvement _I_ don't think makes it worthy of the money, BUT, if it is corner sharpness you want @ wide angles there isn't much option. (Someone else will need to speak to distortion differences.)
I also don't find much of a difference between 16 and 18 insofar as FoV, but others do appreciate that extra 2mm. Again, I would go all out and put the 16-85's money towards a DX ultrawide.
If the 18-55 VR had a higher resale value it might change my thinking on this front, but since you can't get squat for it, it's harder to justify if you're on a limited budget.