John you have to go apples to apple....whether you abort at V1 or you abort 5 knots past...all the factors are the same...
If you want to chase down the over run argument again...then it's simple.....when you calculated balanced field and notice that you had 5000 feet left over...that tidbit of info goes into the back of your head...
If you purposefully plan out that extra 5000 feet..then again...your simply giving your self less options ON PURPOSE...which is a variable I am not willing to accept with passengers in back....by myself...sure.....
I plan for the most layers of safety, not purposefully take out all the buffers, back up systems, fudge factor and safety pillows because financial thift and corporate policy direct that I do so.