I've been in Jag service since 1989, and I still own one today that has 125,000 miles on it. I have seen only one failure of these chains, if you want to call it a 'failure'. It was a chain that set up some kind of resonance at 1800 RPM that set off the knock sensors. Had to replace couple of chain guides along the way, also for noise.
Personally, I wouldn't fret about it.
Edit: Obviously, this is assuming there's been proper care along the way.