m11x is lighter, faster, longer range I believe and just all around a better more updated radio than the m11. go to radio electronic forum and look up the m11x thread and you will get alot of good info.
so i've read the m11x thread and couldnt really find any solid info on the differences between the two besides what was listed above. I guess i'm really looking for functionality differences.
first the fhss 3 is a generation ahead for m11 2,4ghz
more option in the menu
the rx supposed to support the new hv servo
better range
radio is recent too,that help for long run!!!