.....which is what I said at post #10
But of course, you might not be aware of engine low thrust if your probes were blocked.
`if you reach 50% distance of the runway available,before reaching 71%Vr,you`d better stop...
A readout of distance to go would not be the best way to present this, since that would require the pilots remembering numbers for the distance at which they must continue etc., and it would add mental processing time and the potential for mistakes - was it 1430m or 1340m ? And watching a display of numbers counting down would require all of one's attention to the detriment of monitoring the engine instruments etc.
A simple large GO appearing on the PFDs and maybe also the EWD at the V1 point would suffice, with the FMS doing all the calculations so the pilots could concentrate on the centre-line and the engine instruments until GO appeared, at which point they must continue the take-off.
The FMS software code for the GO function could also provide a STOP warning if the acceleration was significantly too low between brakes off and V1.
No numbers, and no interpretation required.