I've never seen, or heard, of this before either, but it doesn't seem like it would work very well. The reason I say that it because piezo's typically like to see a very high impedance to work properly. My BBE Acoustimax preamp has a 2.2M input impedance, and many built-in acoustic-electric preamps are as high as 10M input Z. Since the dummy coil will be acting purely as a resistance and inductance, it will be responsible for about 99% of the signal. Since it's producing none, your piezo signal will likely be inaudible.
Typically, impedance matching is done with a transformer, rather than an inductor. And even then, a piezo probably wouldn't produce enough energy to drive a transformer.
Take this all with a little grain 'o salt. I'm a tech with many years of experience, but I'm not an engineer. Go ahead and try it, and let us know how it works out. I'd love to be proved wrong. Could definitely be an interesting experiment.
