D7000 or teleconverter on D700

I have a D700 camera and various lenses including the 24-70 f2.8, 70-200 f2.8. In the process of planning my next next investment.

I have been thinking of getting a teleconverter lens of X1.7 or X2.0 for the 70-200 to give me a bit more range. I have read that the teleconverters are pretty good now although quite expensive too.

My alternative option is to get the new D7000 camera - this effectively would give me a smaller/lighter 2nd body, increase in pixel density of 76% over the D700, and the option of HD video. The additional cost of the camera over the teleconverter is probably in the region of £500 - £600.

I am assuming the increase in pixel density would give me similar benefits as say using a 1.7 converter on a D700. Not sure if my logic is quite right on this point.

Appreciate any views/advice on this - and is the camera worth the extra cash.

Thanks