I don't know about reaching the selected altitude in two minutes Hand Solo! Does that mean that if I select FLCH at 1000 feet after Takeoff with a set Altitude target of 35000 feet, that it will climb at 17,000 feet per minute!
I believe Hand Solo is correct. For small altitude changes the FLCH logic aims to provide enough thrust to achieve the new altitude in two minutes at the selected speed. That's why the annunciation on the FMA is always "THR" rather than "THR REF" (in a climb) or "IDLE" (in a descent). Obviously, once the thrust reaches the thrust limit in a climb (or idle in descent) it can't do any better so the two minutes goes out the window.