I don’t think the M5 is lacking in bass but rather tuned a little cool. Placement could be critical. Having said that, they also have amazing imaging on and off axis along with glass smooth frequency response through most of the vocal and treble ranges. A little chesty to my ears.
B&W as an alternative... Meh. I just don’t like their treble harshness and no one can convince me otherwise. Monitor Audio Platinum are better directions, or Revel or Wilson IMHO.
Many love B&W, of course, and many love Magico, what I cannot imagine is loving the Magico mid-treble balance and thinking B&W might be another good direction. These speakers don't even talk the same language IMHO and never will.