halbach woofer motor

In my recent erroneous post about a new magnet technology to replace neodymium there began not much of a discussion about the merits of neo magnets in speakers to begin with. I notice that Aurasound has taken it upon themselves to patent the use of neo magnets as at least one of the pole faces in an underhung speaker motor. In the interest of completely eliminating the non-oriented material in the motor, has anyone investigated the use of a double Halbach array? There is no need, necessarily, for the arrangement behind someone's name, except I thought neo magnets could not be oriented most effectively other than in the direction of their pressing before sintering, which makes a true neo horseshoe magnet impractical. The result could be thought of as two horseshoes facing each other to arrive at a pair of gaps with opposing polarity. To make most effective use of this arrangement a pair of coils would need be wound in opposite directions and centered in the two gaps. This would produce no inherent "bottom" in the magnetic path itself, although if the coils left their normal gap and approached the opposite one there would be an abrupt cone braking effect and diving of input impedance. Another plan would be to slightly extend the lower poles so that they met either by elongating the magnet there or including a very small iron spacer. This would produce only one upper gap and allow conventional coil construction.