I've included a list of threads about piezo devices, and this will give you several things to consider.I love the Motorola devices, and I am an advocate of their use. But I would not recommend using them to augment the top octave of a system that has an Eminence MD2001. For one thing, it's difficult to get them within 1/4 wavelength of each other at the crossover point. And for another thing, the MD2001 has about 15dB greater dynamic range. So I recommend using the the compensation network as shown on the schematic.