Even if it's perfectly safe, it will deepen disparities.
It may aslo become really cheap to do this in the future.
OTOH, selection of embryos, by it's nature, will always be expensive.
However, the game will be to select the "best" embryo. This becomes a game of numbers where, on average, the quality of the embryo will be a function of the size the pool of embryos and this will be a function of how much the future parents spend.