quid,
On what jet a/c would you say that MRC speed is "very stable"???
As for speeds, I think we all agree that LRC speed will be a few knots faster than MRC speed. My (and others) omitting the word "speed" makes no real change to the intent of the posts. To recap, you give up 1% range to gain speed stability and a small margin for error (machmeter and airframe drag factor for a start).