Thank you all. I may try getting my hands on the 50mm art to give it a try. I've read that the IQ is amazong but the bokeh isn't. What I loved most about the t4i/30mm Sigma (old 30, not art) was the creamy bokeh. I was constantly wowed by it. Below is the first photo I took with the 30mm, without effort the bokeh was amazing. I haven't been able to recreate the creaminess with the 6D.
forum: Camera Vs. Camera
IMO the 50A is better than my 30 1.4 was in every way.
I used to use my 100 f2 whenever possible over the 30 1.4 because of better IQ, AF, and even bokeh.
Now, I use my 135L and 50A interchangeably on the 6D--and what a luxury that is. I can photoshop to get L colors from the Sigma, but I can't duplicate the detail of the 50A for my other glass.
The bokeh on my 135L is outstanding, but the 50A is pretty good as well. The 50A really gets every ounce of detail out of the 6D's sensor IMO.