The problem with this proposal is the "Torque both cranks the same[probably best to use the same model if possible]" bit. for the same torque applied to the threads, the greased taper will have moved further (the grease reduces the friction between the surfaces, requiring a lower torque on the tightening tool to move the same distance along the taper). So, if we torque the cranks up to the ideal torque for the ungreased setup, the greased setup will have moved further along the taper, causing plastic deformation to the softer part of the system (almost certainly the aluminium crank rather than the steel bottom bracket axle), thus permanently damaging the cranks.