Well it was a complex and slow process, with endless eBay viewings of Canon 35/1.8 and Canon 35/2, but in the end I went with a Voigtlander 35 f1.7 Ultron I found in mint condition. The thought process was that the Voiglander was going to provide me with better DOF subject separation and sharpness wide open. The Canon 35/1.8 seems rather hit and miss. There were so many quality issues with examples of the Canon 35/1.8 that in the end I thought (known haze issues aside with the Voigtlander), if I can get a good copy of the 35/1.7 then it would solve the problem.