Hi Depechie, I own the 1,8 and haven't compared it to the 1.4...I know that is your question but, I am very happy with my lens. According to reviews the 1.8 is a steal when it comes to prime Nikon lens's. 100.00 dollars. I didn't hesitate to spend the 100.00 and I find the 1.8 to be crystal clear.
I have a Nikon 50 mm lens 1.4, very good lens and take sharp clean image, I recommend you should get the 1.4 if you are interesting in very sharp image, and it also shoot well in very low light situation,