The RAW files produced should be much less noisy in the shadows than in conventional single-shot captures. However I wonder in which situations will this mode be available since in low light conditions the overexposed capture (which must be at least 4EV overexposed to reach 12EV of DR) can require a quite long exposure time.
Does this subject deserve two threads?
The CX1's sensor is 7.7mm diagonally. Full frame 35mm is 44mm diagonally. For a given DoF there's a 5.7 stops difference in aperture, approximately.
That means, for example, that in order to get a shot with FF 35mm that has the same DoF as a shot with the CX1 used at F3.5 and 1/800th second at base ISO, you would need to use the FF DSLR at F22 and 1/20th second, at the same base ISO.
It's not clear what the time interval is between the 2 shots taken for HDR purposes. It should be very small since the CX1 is capable of shooting video at 120 frames/sec, so let's say it's 1/120th sec (although it's likely less). In this example, the total time for 2 shots, 4 stops apart, would 1/800th + 1/50th + 1/120th = 1/35th sec (approx).