Well the Airbus opinion on the matter (refer the STOP/GO FOBN) which reflects regulatory definitions of V1 being the maximum speed at which a takeoff may be discontinued is:
V1 is considered to be the end of the STOP or GO decision-making process. Therefore, at the latest, this decision must be made at V1, so that the Captain can initiate the STOP actions as close to V1 as possible: V1 is indeed a decision/action speed.
Logic says that if the decision is to be made
by or at V1, then the call can’t be made
at V1.
Having said that, look at the ASI permitted discrepancies from CM1 to CM2 ...