the 16-35 at 16mm on a FX body (D800) is about the same wide as the 10-17 at 10mm on the D7000 (DX). But the wight and size is certainly an issue...
This is incorrect, probably a typo.
The 16-35mm at 16mm (on FX) is about the same angle of coverage (a little over 100˚) as the 10-17mm at the 17mm (on DX). The 10-17mm then goes a lot, lot wider ,when zoomed out. In short there is very little overlap between these lenses - although both are useful.