if I understand the schematic correctly, the opa445 acts as an integrator. Could it be that if the parts are well matched - and the opa445 is not in - there is a steady decline of the offset? Which in turn would mean, that the opa would correct all the time in the same direction with a declining rate? And thus overshoot?
Therefore the whole system would start to swing slowly but instigates over time even to V+?
How would one have to measure the amp with an open loop to get at the bode diagram? Would a bode diagram help to find out if the system - in that particular constellation - is getting unstable? Because maybe someone could post it?