It actually works very well on the SFC. Less weight on the train gives less stress on the boogies which in turn gives a smoother ride.
TBH I'm not even sure any SLC uses similar dampeners. The new SLC uses a stiff construction and I think the old ones do to.
[attachment=0]wildwood2008_03.jpg[/attachment]
you can see the upstop wheels not quite touching the track!
on the SLC hang and bangs, one of the problems is that the bogie can move up and down and back and forth on the track, amplifying the banging. Sometimes you come flying into the final brake run and the wheels keep spinning because they don't touch the track.