It's the same sensor as in the other GXR A12 camera units, although it has been optimized for use with the M-bayonet RF lenses.
Comparing the image output to my other cameras of recent years, in broad strokes it's on par or better performance than my Pentax K10D, Panasonic L1 and G1, and Olympus E-1. The Olympus E-5 supports ISO 6400 in addition to the ISO 3200 supported in the GXR A12 module, but the GXR's noise and quality at ISO 3200 is right on par.
The E-5 also has the least anti-aliasing of any of the other cameras (whether it has none or simply very little I"m not sure or) so it is a good comparison to the A12-M with respect to acutance. It's a smaller sensor (13x17.3 vs 16x24 mm) so slightly higher pixel density, but with equivalent FoV focal length proves to have very similar to slightly better acutance to the existing A12 AF camera units, and my quick test of Uwe's A12-M shows it to be in the same ballpark. I think I'd rate the E-5's sensor and supporting electronics slightly better performing on that basis, since it is somewhat smaller, but i'm splitting hairs there.
So whether this sensor is "outdated" or not makes little difference to me. From what I've seen, it is an excellent sensor with outstanding acutance, dynamic range and sensitivity. The sensitivity and dynamic range is as much as I need. Presuming that its optimization for the RF lenses it was designed to work with works as advertised (and it seems to), I see no problem at all in adopting it as my standard camera. The E-5 has advantages in speed and responsiveness, but I only rarely need those qualities ... the advantages of the GXR+A12-M in size and use of Leica M-bayonet lenses is quite valuable to me. It's also nicely less expensive than the E-5 body.
Of course, I retain the freedom to change my opinions and evaluation once I've had a month or three to work with the A12 Camera Mount. Mine should arrive next week... And I'm eager to have it!