FWIW, I went from mall toys straight to mcpx, and I love it. Don't know about the nano.  The nano is supposed to be hotter than the mcpx. Def. smaller. The throttle setup on the mcpx took some getting used to. If you chop the throttle (which was what I was used to doing), it slams into the ground because the rotors go into negative pitch. Stay low when learning, and ease off throttle at the first sign of trouble.
Best,
GB