The comparrisons to Otus is interesting. I wonder if the Otus would be relatively better on a D800?
Maybe the Canons 21mp sensor is the limiting factor?
I was wondering the exact same question. An example is this (from DXO)
Using the D3 the e Otus render 12mpixels against 10mpxiels of the 50mm f1.4G (20% better)
With the D800 is 29mpixels against 16mpixels (81%) and it's not clear that the Otus has reach its limit.
In fact the Otus render 21mpixels on the D7100!!! against 13mpixels of the 50mm f1.4G lens.
That means that the Otus could render far more than 29mpixels in the next generation sensors.
By the way the 135mm f2.0 Zeiss is almost as good as the Otus it has a fraction of the price and a very good angle for portraits.
And yes it does not have auto focus (grrrr)
So lets wait and see. In any case It seem clear that it will totally kill the 58mm noct as a general use lens. For astro photography the noct should be better.