G., still sideways to the dilemma. Why DRT set to an identical N1 provides higher PTOM on ASDA limited case is well understood, although rarely seen spelled out as clearly as you just did.
The different RoE is being scrutinized. Having an engine fail at their respective min V1 will be covered on both sides by their own pre-determined Vmcg/a limits. Both methods are pure pilot manager's choice (cutting some deadwood arguments here) to save the engine costs. DRT carries an extra book of perfomance tables, alright.
FDR sheds a light, noting that (as long as) DRT is considered an equivalent full certified standard there shall be no more constraints imposed. Which is a get out of jail card.