Hey Simon,
Another vote for the Sigma 35/1.4 here. I am generally not a fan of third party lenses (other than Carl Zeiss) but this one is a winner. I spent *considerable* time (somewhere north of 6 different testing sessions across many weeks) testing it against my other wide angles with my D800E (Zeiss 21, Nikon 24/1.4G, Nikon 28/1.8G, Nikon 35/1.4G and my 24-70/2.8G zoom) and it easily won the competition against the 35/1.4G in every aspect of performance EXCEPT flare resistance, where the Nikon was markedly superior, and if one were to get subjective, I thought the Nikon bokeh was a bit better. This included testing at every possible distance range I would ever see myself using the lens in, from studio work through infinity/landscape, all controlled, proper testing on a heavy tripod rig, remote release, focus bracketing via live view and so forth. Short answer: I just sold the Nikon 35/1.4G; in particular the distant corners/edges for landscape type targets were rendered better with the Sigma, and even in studio work, the sharpness advantage of the Sigma is noticeable. Only my Zeiss 21 is noticeably any better in the center, which is saying something. I even tested the Sigma against the Zeiss 35/2 and Zeiss 28/2 and preferred the Sigma.
So, to make a long story short, I hope you try another one; this is a truly state of the art lens if you find a good sample.