I confess I have never understood the philosophy of a transfer of control DURING a rejected takeoff, particularly an "unambiguous" one. If as Commander (but PNF) I say "STOP STOP STOP" during the takeoff roll, I expect the PF to stop the thing, not to simply say "you have control". (Obviously they can call for appropriate items to be carried out by PNF, and in due course perhaps hand over control, but the first actions are all theirs). Why would you want a flurry of changing hands at the instant of peak stress?