I think the players who would do the kick curve are probably more used to bar boxes. On a barbox it might be the right shot because if you hit it, it has a high chance of going in and 2 rail kicking the 5 to the center of the rail with the cue ball up table isn't much of a safety on a barbox. On a 9 footer the 2 railer is a much stronger shot. Good luck getting it to curve as diagrammed on a 9 footer, not to mention you'll more than likely sell out.
You think right sir.... The two railer is still the best shot even on a bar box (maybe even more so than on a 9'er).....