Mr. Selfish,
The constant angle technique was what I was taught, as well. A NASA program about 20 years ago showed that the best way to spend the power to takeoff was to accelerate IGE, so the excess power was available to get you to some forward speed in less distance. Even the first few knots is worth a bunch, in an S-76, 10 knots of wind or forward speed will allow 1000 pounds more performance from the rotor, making the climb angle at 10 knots much steeper, so the distance you spent getting the speed is recovered in the climb phase.