Arent we all getting a bit carried away with numbers? We are beginning to sound like fixed wing dicks.
Surely you fly the cat A profile (speed/height/attitude/Rate of climb/descent) for your scenario rather than blindly pull a power figure and adjust attitude to cope. Flying the profile is what keeps you alive, and the publication of power numbers is to give you a starting point.
As above, the newer types tend to publish a power margin above OGE or IGE so that those anal enough still have a figure to argue over, those who use judgement to suit the given conditions are still permitted to, and finally those who cannot operate without everything spelled out can still fool everyone into believing they can fly.
But it is ALWAYS the profile that gives you the best chance of getting out of jail - so use it.