I had a chance to try the XPro1 and 35/1.4 at CES. From my point of view it is the most promising mirrorless camera system yet, with a range of high-quality, fast, SMALL prime lenses to be available from launch. The Sony NEX-7, while lighter, felt cheaper, flimsier, and less stable to me. The hybrid viewfinder of the Fuji is also quite ingenious, allowing you the best of both worlds: EVF for TTL adjustment of filters and exacting exposure setting, OVF for manual focus in low light and rangefinder-style shooting of moving subjects.
Of course the Fuji is still not finalized, and nor is the price, but it certainly looks like a top-of-the heap contender for the title of best mirrorless camera 2012. Only if Samsung has an ace body up their sleeve to complement their line of NX lenses (perhaps the most comprehensive, short of m4/3, on the market), or unless Canon pulls a rabbit out of their hat with a full-on mirrorless system (as opposed to the half-baked G1X) would I see that changing.
FWIW, I carry about 10lbs of camera gear on most of my trips (including Mts. Whitney, Shasta, et al) (Nikon D700+2 lenses+tripod), though I do have a Sony R1 which is a great camera for lighter outings where photographic opportunities are low. I'd love a camera with the image quality of what I use now that's half the size, but I'm not holding my breath. I would rather work harder and deal with the weight, than compromise my ability to get the best image I reasonably can.