GMAT is just a part of the equation. There are just too many factors that goes into admission and scholarship selection... Generally speaking, sure, 750 is probably better than 710... but probably only matters by a little. You can check the profiles of those who were accepted last year... not everyone had top GMATs.
You should apply. If things don't go your way then apply next year (then retake GMAT). 710 is around CBS/NYU average not bad but not great (720-750 range would be better). But again, GMAT is just 1 factor, and 710 is enough to try this year.