D800 is an amazing camera but maybe is not the best camera for a portrait photographer that is not a fashion photographer and so doesn't need the to blow their photos as much .
The extreme definition of the D800 call for very good quality lenses, like the 85mm 1.4g or the 105 micro 2.8, or even the 70-200 2.8, in order to take in full advantage of that quality. The result with the D800, at least for portrait, are that one can see all the small skin imperfections all the, sometimes undesirable skin texture and details, that have to be corrected afterwords on photoshop. Your camera with the 85mm 1.8g will give amazing results if combined with a good workflow on photoshop or equivalent software. On the other side the d800 have not yet resolve all the problems related with the small pixel size and noise that let for instance that the canon 5dIII with less MP (22MP vs 36MP) but bigger pixels, win the race (for most applications at least...).
Have a great day, (and good photos to...)
António Amaro
