[Aero Engineer]
I think the problem that was mentioned by Cubdriver with not climbing is related to how a turbojet engine produces powers vs thrust. By definition, you must have forward speed for a jet engine to produce power. Since a turbojet engine operates at a (mostly) constant thrust across the entire airspeed regime for a given density, when the airplane is slower, there is less power available. Rate of climb is directly related to power available(angle of climb is determined by thrust available). As you get to the backside of the power curve, your power available decreases with airspeed. I can see how you would get to a point where you would need to accelerate first before attaining sufficient available power to get a satisfactory rate of climb.
[/Aero Engineer]