EPLS
All you are doing by using an increased V1 is increasing a take off performance that is limited by climb gradient rather than ASD (hope I am correct) and increasing the V1 to a point that the ASD is limiting, thereby being able to increase the climbout speed and therefore gradient.
The disadvantage (or as you put it the penalty) of using increased V1 is that on a limiting takeoff an engine failure just before V1 would mean that the aircraft should come to a halt on the end of the runway.
(At this point a performance expert is going to write "not strictly correct and give you the legal explanation).