The problem that was originally put forward has to do with having lots of runway available ahead of you- probably more than the CAT A data had assumed.
One helicopter I know has a definition of a long runway as bewteen 1100 and 1700 feet in length. Not much help if you are in front of a 10,000' runway to be sure.
The best advice I could give is to consider using the landing distance for the 'long runway' case, as a guide. But then what do you do to make sure you can decelerate and stop in that distance - maintain some slow airspeed and low height above ground until you are sure you couldn't make it? That's not smart either.
Yet another place where we are nowhere as cut and dried as our fixed wing brethern. And another place where we need some reasonable guidance.
But why are we taking off from runways anyway? That's like making all trucks load and unload at railway stations...