Besides being a lovely photograph, your comment "not a spec of digital noise to clean up" is interesting.
Buried in Fuji's marketing material on the X100, they mention a great deal of design effort was invested in removing heat from the sensor. I suspected the X100's outstanding signal-to-noise is partly due to keeping the sensor region as cool as possible. Your observation about low noise for a 30 sec. exposure could be consistent with efficient sensor heat removal.