olddog,
I use a 521 delivering over 400hp to the rear tires. It has run at Sebring, Gainesville and lots of other tracks while accumulating over 19K miles. Oh, yes - the track time is spent using slicks on all four corners and running WFO wherever possible. More anecdotal evidence.
Also, if you really look closely at the Jag rear, you'd notice the lower arm/hub construction will restrain a couple of degrees of freedom if the axle does come adrift. The result is probably not as catastrophic as you anticipate.
I do examine all six of my u-joints once a year or so, grease them and tighten bolts where needed. Nothing that an average high-stress user wouldn't do in the way of maintenance.
No offense here - please don't interpret this the wrong way - but I think this worry is like the old bumblebee theory: from an aeronautical engineering perspective it is concluded that the bumblebee's design isn't correct to allow it to fly. The weight is too high, the wings too small, the aerodynamics all wrong. Fortunately the bumblebee is unaware of this, so it goes ahead and flies anyway...
My experience says there are far more injury and fatal wrecks in the Cobra world resulting from right-foot disease than any other cause due to the very high power to weight ratio, short wheelbase and overuse of the gas pedal. I have personally known several who were killed or injured this way, where no mechanical failure appeared to be involved. HeII, I flipped mine taking driver's ed (on street tires), but that's another story - one Jag rear wishbone was broken at that time from the impact, and was not a cause according to our failure analysis expert.
So unless you can point me to some hard evidence, I'll continue to use mine vigorously on the track
and gently on the street!
Regards,
Tom