Well, I have both the M11 and the Q3 43. The Q3 is almost the same size and hardly compact. But it's half the price because thee liens is included and it has autofocus, so I am not surprised at all the Q is more popular.
The Leica M11 is one of the most unusual cameras on the market, as no other major camera manufacturer offers digital rangefinder cameras. This expensive full-frame camera, which lacks autofocus and image stabilization, apparently does not sell nearly as well as Leica's most expensive compact camera.