The flight director tells you what you set it up for. In my last aircraft I had performance charts for clean and take off flap so the answer in that case is if the engine stops I had a known speed to slow to and could plan my performance in advance.
Whilst I would have done my planning based on the engine stopping at V1 and climbing at V2 to acceleration altitude if I was at V2+20 with the flaps up or even retracting when the engine stopped I was already above the profile for a V1 fail and my climb angle was better at V2 clean.