85mm f1.4G or 1.8G for D800(e)

I have a D800E and am generally thrilled

I am deciding between the 85mm f1.8G and f1.4G for portraits and also general people at a slight distance

This will be a lens I will only use 10-20% of the time, as I use wides most of the time.

I will be using in low light, but not all the time.

Is the cost diffference between these lenses worth it ? I am happy to pay the extra if justified, although I prefer the weight of the f1.8.

I am mainly thinking about:
1. Centre and corner sharpness at f1.4-f2 (90% of usage will be here)
2. Micro contrast
3. Colour balance

Anyone have used both and can comment ? Preferably on the D800
thanks in advance