The direct-mount centerpull has real advantages over canti's, including the posts being much closer to the crown, so the posts flex a lot less.

A booster-plate for centerpulls can easily be much shorter and thus lighter and more elegant, if it was even needed.

I've messed around with centerpulls, and this pair, modified with cord pull straps to each pad and home-made booster plate was good enough for wet descents on the World Cup XC circuit.
They're still going strong along with the bike in CX guise, though by now the rear caliper's bushings have worn very loose due to the thin stay's flexing in twisting fashion while the pads remain parallel to the rim surface under hard braking. A booster plate on the rear caliper would have prevented this.
BTW, some bikes were fitted with "push" brackets that fed the pad's braking forces directly into the stays instead of into the pivots, much like the pull straps on my front brake accomplishes.

Centerpulls would also seem to have less overhang outside of the fork blades and seatstays than canti's, so less chance of hitting things or snagging the rider's leg.