Go with what floats your boat. The x10 did it for me. The familiarity from your x100 I would think would be valuable but once will "click" with you. The x10 is a bit smaller than your x100 I am sure you know, but I have to really "feel" the camera to enjoy it. As a backup to my x pro it made sense to me.
I happen to be in that place right now where I am really enjoying my gear, and with that, new inspiration....see which one gives you that!!!
The Sony's IQ may in fact be a bit better but I have seen your skills in previous posts. It won't matter which one you choose....you'll get great photos.