No need, 50L is king.
I can agree with that, I love it for sure, but only on the 1d X, never found any other camera that could tame the AF precision and the only camera I really felt i I got it 100% with calibration. Do I like the trade-off of sharpness for the creay bokeh, of course, I don't shoot test charts. And coupled with the 1dx it really shines. Tracking my kids at f1.8 results in some great captures at 12 fps. It's small light, built like a tank and sealed. What more could you want?
I would keep it even if I bought the Zeiss 55...