After playing with the 23 and 56 on a X-Pro-1 and XT-1 for a bit I observed the fly-by-wire focusing experience is highly dependent on the lens motor and lens-collar sensor technology and slightly dependent on the bodies' CPU speed and firmware.
I would like to stress the differences in the prime lenses' focus collar feel I discuss below are, in my view, quite minor but real. For all practical purposes both bodies provide similar utility for lens-collar focusing.
The method used for both lenses is somewhat different because the 23/1.4 has the push/pull feature. It took me a few outings to get use to this. This is the only operational difference except the 23/1.4 also has a DOF scale.
Both focus using fly-by-wire technology. When you reach infinity or minimum distance the collar just keeps turning. Both are up to the task of fine focus adjustments fast lenses require.
The 56/1.2 collar has a very firm and tactile feel. The change in focus on the XT-1 is continuous and smooth. In fact, through I am not particularly fond of focus-by-wire, the implementation on the 56/1.2 is difficult to fault. The throw is well suited for the fine adjustments a f 1.2 lens might require. The lens is a little bit noisier on the X-Pro 1. Fine adjustments work just as well, although the view in the finder is just a bit less smooth.
My experience with the 23/1.4 is similar. Except the lens itself is slightly less smooth and noisier compared to the 56. Again, focusing with the XT-1 is a bit quieter and smoother than with the X-Pro 1.
I also tried the 10-24/4 on both cameras. On the XT-1 the lens-collar focusing is superior to all six Fujinon primes. I was surprised. I would be willing to bet most of us would not guess the 10-24/4 focus collar is fly-by-wire until we realized there is no mechanical stop for the focus collar. I would say it's silent, but I'm sure someone with more sensitive hearing will claim they can hear it. The EVF view appears continuous at reasonable light levels (EV 5-6). Smoothness and EVF quality decreases as the light level decreases. If I underexpose the EVF by more than 2 stops at ISO 1600, performance becomes highly compromised. Again, the X-Pro 1 is a bit slower.