I've gone through 8 different Vortechs before I finally found 5 that did'nt have reliability/noise problems. At $500 a pop you'd expect a little more out of them. They're a really cool powerhead and i'm pretty happy with them. But, as these start to break down I will most likely be replacing them with the WP40s.
Here's a long demonstration on them. I could'nt watch it all but you might be able to sit through it.
http://www.youtube.com/watch?v=YXfEwdNG_wg