IMHO the autopilot in Autoclimb Mode is all wrong! First of all it only has one default setting, somewhere around 1,000fpm [in a B17 anyway]. This is just not realistic.
And no matter what your attitude is at the time it's engaged [whether you're in level flight or already in a climb].... the aircraft balloons skyward & kills all, or most, of whatever airspeed you had built up until you're somewhere just above stalling speed - then settles into a climb rate somewhere around 20-40fpm or so higher. This is also definitely no where near realistic.
When Climb Autopilot is set you should be able to smoothly pull back on the stick & lift the nose - and as long as you stay within the performance envelope - engage the autopilot and the aircraft should maintain the current climb speed & attitude [there may be a slight momentary drop in airspeed & altitude - then a recovery - while the aircraft "settles" into its new attitude.]
Doesn't this explaination & definition sound more like RL? It is you know.
Can the Autoclimb Mode in AH be changed to reflect this modeling?