Henra,
John D was very careful in explaining that the decay was calculated by the SA guys in response to an accident investigation: not done in 'real flight', and also that the number 'was in the 60% range' which could be 69%!
For you to allude to a drop to 60%Nr can be considered is a bad move on a helicopter forum, since it can morph into an assumption by some and then, before you know it, we're into the 30 minute S92 run-dry scenario where it becomes a firm belief.
I hope that you can see the sense in modifying your post to remove your reference before it becomes assumed to be valid.