I think the most important thing is "How many of these things need to be done before adulthood to function?"
The degree to which you're able to consent to these sorts of things is crucial. If your IQ booster shot only works on infants, you'll have a boatload of people who resent never having the opportunity to get it because of their parents' decision, and an equally frustrated bunch of people who resent the forced pressure of having a gift they never wanted. It's not like we don't have these sorts of problems already with education, the existing genetic lottery, and such, but it certainly does exacerbate the whole issue. EDIT: And unlike most of the existing similar scenarios, it's totally under the parents' control, finance aside until the next paragraph.
As for competition, that's a totally valid argument that is best handled by adjusting society in order to render it moot. As I see it, there are three possible futures. Ignoring, for the moment, the one where we're extinct, we can either get used to the idea of a dystopian hellhole where you're expected to do entirely pointless work for your entire life to justify your existence, or a much nicer world where you don't have to justify your existence in the first place because we have the technology and resources to support you anyway. This is independent of transhumanism, though, and is more a consequence of technology's inevitable forward march in general; where we end up seems to be largely dependent on politics and the functionality of space travel (gotta have 'dem extraterrestrial resources), and both are looking mighty dismal these days. It winds up being pretty off-topic, though, as a consequence of being more of a parallel issue. In any case, the effects of transhumanism would mirror the world it winds up coming about in - if we're in the stratified hellhole world, it's just going to make things worse for the non-oligarchy folk. Then again, in that case, us plebs are fucked anyway.