The most important practical concept when teaching the early ab initio students is to make sure they can recognize by looking at the natural horizon through the windshield what the pitch attitude of the aircraft should be to fly level for that airspeed. The ability to go directly to the correct attitude is the corner stone of the ability to fly accurately. Sadly many licensed pilots can't do this and compensate by chasing the instruments.
What does this have to do with the thread topic ? Well IMO, everything. The pitch for airspeed power for rate of descent or point and power styles share one defining nexus. The ability to set and hold a desired pitch attitude.
Personally I teach a blended method. I start with a pure pitch for airspeed and power to control the flight path because it is consistent with what is taught in the early climb/descent lessons and because it builds a life saving reflex, lowering the nose when the airspeed is too low. As student skills develop I find the students naturally gravitate to a point and power technique because it is provides a smoother final approach. But by this time they fully understand the interrelationship between changes in power and changes in attitude and can fly accurate airspeeds at different power settings.
Finally there has been much discussion about the back side of power curve. The point of the slow flight exercise should not be to fly in the slow flight regime because unless you are into serious STOL work there is no reason to be there unless you are in the landing flare, but rather to teach early recognition of the fact that the aircraft is entering the slow flight regime and effective recovery into normal flight without a loss of altitude.