From a technical standpoint, increasing the box size of any sealed alignment reduces power handling. There's less of an air spring the larger and larger you go with volume of a sealed box alignment. I seriously doubt the DIYMA is happier in 1 ft^3 with 1500 watts than it is in 0.5 ft^3 with 1000 watts. Either way, the cone can't handle the power. Thermally, that big coil can soak up the power, but the rest of it isn't up to par. But with what most people run on the DIYMA (less than or equal to 500 watts) there's no problem. But saying that increasing box volume increases power handling is like saying that doubling your horsepower slows your car down.