The easiest and surest way to make 77 mm work is to stop locomotives abruptly by activating their f4 function once they reach the IN sensor. Careful calibration of the V_min and the deceleration rates of the locomotives may also work, but the final outcome is probably not much better than the abrupt stop.

If this is not desirable, I believe 172 or 188 mm is better. Even in this case, adjusting V_min and the deceleration rate needs some care, but the margins of error are much wider and the resulting behaviour of the locomotives is more pleasant to watch.

EDIT: Perhaps in a staging area abrupt stopping is acceptable as it helps maximising its storage capacity. In this case, the f4 function trick appears to me the best solution, because it leaves you free to set the V_min and the deceleration rate as you wish for nice performance elsewhere on your layout.