Well, I have to eat some major crow here. I was riding to a conference today when I felt a sudden change in the position of my saddle. My first thought was that one of the saddle rails had either broken or pulled out of the saddle's base. Closer inspection revealed that one side of the Rinsten Spring had broken. I have about 800 miles on the spring.

So, I offer my apologies to Wileyrat, who suggested I needed 4,500 miles to establish reliability. Now, in Devil's Advocate mode, the failure of one unit doesn't mean the product is badly or even fatally designed... but at this time, we seem to have an apparent failure rate of 100%... this does not inspire confidence. I've got another one of these on order, and I'll still give it a shot if I ever get the thing (see the following for the reason why).

And, I have the answer to the question posed by JanMM and RGConnner: "What if it breaks?"
You can see from the attached images what happens. The saddle tips instantly onto its side; this is obvious to the rider. I was a couple miles from my destination, so I was able to keep riding. If I'd had to go much farther, I would have removed the spring and re-mounted the saddle. I have a small amount of satisfaction in this matter in that I predicted that *if* the spring failed, it would probably do so in a "fail-safe" mode... ie, not castrating the rider.

Attached are images of the broken spring, including a "macro" shot of the fracture face. I think this is a pretty standard "cyclic fatigue" fracture. Was this because of a surface defect that acted as a starting point for the fracture, or was the steel spring operated out of its elastic range? During its short life, there was no sagging or apparent plastic deformation of the spring.

Well, that's the news from Lake Wobegone. At least no one will say I wouldn't admit to being wrong!
Steve