My fear is that, an "enhanced" human will significantly outperform it's peers and thus will gain advantage in all aspects of life, that is the point after all. Those advantages will be seen as unearned and thus the "losers" will become jaded and blame the technology - or rather the person's access to it. Someone who was conceived in vitro doesn't pose a threat to it's peers from the perspective of abilities by virtue of being in vitro.
Just like you see jealously now for disparities in abilities, I worry it will be magnified once people start upgrading.
That's without even getting into the "who can afford to upgrade" part of it.