Nick
You make the point about turbojets having ample thermodynamic power at low altitudes as a result of their design requirement to be able cruise much higher. Can a similar design concept be applied to Helicopters. That is, designers set performance goals to the aircraft based on a cruise height eg 10,000 feet (no oxy) and say we want max OEI payload, maintain height (dont worry about using driftdown techniques), suffer only a 10% loss of TAS, full anti ice & heater on (I hate being cold). From this then surely the flow on effect would be helicopters with engines of similar power excess and thus "CAT A" for free.
The selling point could then be related to cruise safety, performance and comfort and "hey we can even land and takeoff on one engine but we will throw that in for free".
In the fixed wing (jet/turboprop) world you lose an engine and you usually still get to where you were going or end up back where you started, but with helicopters generally you dont as they lose so much cruise performance that an intermediate alternate is required, this is most felt in the medium twin market.
Anyway IMHO engine power is a bit like diet coke you can never have too much, nothing like being able to lift heavy things I say.