Engadget Mobile (the source of the picture) recently reviewed the HX1 and compared it to the Jawbone Prime. The verdict? “[I]n every other meaningful metric, we found the HX1 outperforms the Prime.” The review explains this verdict in detail.
Bring the noise: Jawbone’s NoiseAssassin 2.0 vs. Jabra’s Noise Blackout compares the different noise cancellation technologies of the Jawbone Prime and the Jabra BT530. Interestingly, the substantially cheaper Jabra compared favorably.
The HX1 may be my next Bluetooth headset. Unless something better comes along in the meantime.