Nice discussion.
8che tis might clear the air for you.
Derated take off Thrust (Fixed Derate) permits a higher takeoff weight when performance is limited by VMCG. This is because derated takeoff thrust allows a lower VMCG. (particularly sensitive when operating a 200LR with 115's hanging on the wing)
furthermore, derated takeoff thrust may also permit a lower takeoff weight when the takeoff weight is limited by the Minimum takeoff weight requirement.
sounds as clear as mud right
