Some of you may be interested in how the trough produces the substantial reduction in bearing rumble and motor noise (i.e in the 20- 80Hz region) it does.
It's because the stylus 'sees' this noise coming from both the plane of the platter/record and from that of the deck of the headshell above it, 180 degrees opposed or 'mirrored' to the platter, hence there's a net phase-cancellation.
This isn't just theory - there's an article by Max Townshend floating around somehwere with measurements and spectrograms (with/without damper) - the reduction in spurious LF is not trivial. Many people have noticed and remarked on the quiet or 'dark' background produced by the various Rocks.
That's just gravy though - the real benefits are in the stability imparted by this removal of spurious LF at the stylus (effectively, locking together of cartridge and platter from 20Hz upwards) - improvement in bass fidelity, tracing and tracking, etc' etc'.