Having the minuscule XT-30, I don't like bulky and heavy optics on it. But when I used the 56/1,2 for the first time in a store, it was love at first sight. I have never regretted it.
I have that lens for years now and love it to the core. The only time it lets me down is in really low temperatures when its AF motor tends to freeze, rendering the lens useless. Until it warms up, when everything goes back to normal. And I'm a winter person. Damn...
I do not agree when ou say the AF is "fast". From a distance of a few meters it hits the subject a bit better, but closer moving subjects like moving children in the near field are hard to get in focus. I used the lens for 8 years for portraits and it is good at that, but the new one is better in virtually every respect: sharpness is much (!!!) bettered, minimum focus distance is much closer which again gives much better bokeh, but the focus motor is still not LM (linear motor). The old one has (or just had) a huge cashback and could be bought (in Germany) for just under 500 Euro, but I'd still recommend to save a bit longer and get the new one. Just like the new 33/1,4 versus the old 35/1,4.