Upload & Sell: Off
It is very unclear to me what you are trying to accomplish with your new purchase. If you like the current 35mm lens, use that. If it isn't useful to you, sell it and get something else.
I hope you aren't hanging on to a 35mm lens that you don't find especially useful because the words "Contax" and "Zeiss" appear on the product. If so, sell it to someone else who places greater value on the words than on the functionality of the lens and use the proceeds to purchase a lens that works great, produces fine image quality, and which will be more functional for your intended use.
My two cents worth...
Hey, I need help picking an AF lens for social occasions and general use.
I currently own:
35/1.4 Contax Zeiss
100/2 Contax Zeiss
I love the 35 field of view and ideally would like the Canon 35 1.4L but I really don't want to sell the Contax and it seems a bit ridiculous to have two expensive lenses of exactly the same focal length and aperture.
I'm currently thinking about a 35 f2 for about £217 new from Jessops, or a 2nd hand Canon or Sigma 50 1.4. Are there any others which would work well in low light which would be similar in image quality to what I already have? Suggestions please!