Mutt. With all respect to your high qualifications. My concern about using higher V speeds than is necessary for the actual BRW is that it is not a Boeing approved procedure - If it was, and there were significant advantages accrued, then I am sure that it would have been recommended by the manufacturer.
Deliberately using V speeds that are in excess of that needed for the actual weight, simply because it is perceived as too tricky to fiddle the FMS, would cause a good QC to rub his hands with glee in court - in event of an emergency on take off that turned into an over-run due excess unnecessary speed additives. Slippery runways come to mind here.
History has shown that there are significant hazards involved with high energy aborts - so what is the point of holding down on the runway to get extra speed when it is not needed?