I am a X100 owner, and I took a quick look at the X-Pro 1.
Personally I like it, it feels really well in your hand, the buttons are better than X100, there is finally a quick menu, no more stupid RAW button and the AF selector is way better than the toggle switch.
My only horrible downer was the worse viewfinder, honestly, darker and smaller, compared to the X100.
The massive wow moment came with almost instant on, or rather instant on, I didn't feel any lag. That is on from off. I wasn't able to try on from sleep, but if on from power off is so fast, on from sleep will be as fast.
And to anyone: Stop comparing ANY camera that only looks like a rangefinder to a Leica. Nobody takes your precious Leicas away, nobody.http://clemens-and.nihongonauts.com/post/18377857955/a-second-with-the-x-pro-1