I haven't tried the spider system but may.
As to the Black Rapid, I bought it about a month ago and have used it quite a bit, most recently at an event this past Saturday, a surprise 50th bday party which was thrown by a wealthy friend for his sister, recently retired Deputy Inspector NYPD. You can imagine the size of the event: At least 150 people, large ballroom, DJ, whole ball of wax.
The strap was excellent. The camera does not swing around at all. And I'm not sure how they do it, but it is absolutely weightless. I don't feel the strap pulling on my shoulder in any way, shape or form. Very quick to grab, shoot, and place back down. And I was using my D3, easily the same size and weight as my former 1 Series, with the new Nikon 70-200 f2.8, and a SB900, a very large flash, along with the Elinchrom Skyport transmitter in the synch socket, with the approximately 6 inch cord wrapped around the hotshoe.
I am jonesing for the spyder though.