Never seen or heard of.
What TV and trailer do you have?
Are you using a properly sized WDH?
Often, I believe bounce (or "porpoising" if that's what you have) is caused by using a WDH that is right at or over it's weight capacity. The springs are not stiff enough to dampen out the oscillation, so they act like the springs that they are.
This system seems to be the right complement, just like automotive shocks complement automotive springs. But not sure it's worth whatever they cost if a spring-bar upgrade would do the trick.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller