Having been away for a while training, I note the clouds of dust on engine performance have cleared, thanks no doubt to the downwash created by Lu and Nick's discussions.
But seriously, the point seemed to be missed by Peter that the power available is not a function of density altitude. I hope the rest of you got the message though. It is a myth.
For those that need further education, either look at the power check charts for a turbine engine for extremes of temperature and pressure altitude that make up the same density altitude, or if you have sufficiently underpowered helicopter, look in the hover performance section and note that temperature is shown twice - with significant reductions in maximum weight to hover at high temperatures.
And I'm not sure if the list is for helicopter pilots who need to know what is true and what isn't, or for those outside the profession looking in, who have a whole other set of myths - like if the engine quits you're going to fall out of the sky like a brick.