What mm's experiment showed was that when an aeroplane is trimmed it is not trimmed for a speed, whatever the pilot may think he is doing, but for an angle.
Save for those aircraft equipped with angle of attack indicators in the cockpit, you can safely and correctly assume that you trim for speed. That's what's before you, and the aircraft is indeed trimmed for speed.
Large pitch changes or airspeed changes aren't necessary when an engine failure occurs. Fly the airplane back down.
In most light airplanes, your climb speed is very close to your best glide speed and if the airplane is trimmed for takeoff, it's properly trimmed to come back down. A power loss is not the end of the world; it's a transition from a climb to a descent, and from power on to a glde. Nothing more.