According to Leica Rumors, Leica is planning to release another firmware update for the M9 to address some additional SD cards compatibility issues. The new update will probably address new SD cards that were announced after the last 1.176 firmware update. Some M9 shooters have reported problems with the SanDisk 64GB SDXC Extreme Pro Class 10 UHS-I card.
Digital Camera Review has just published an in-depth article on the M9-P. Check it out here : http://www.dpreview.com/articles/4052788152/shooting-with-the-leica-m9-p