I agree - we're a long long way off being able to accurately predict the impacts of genetic changes, particularly given effects like pleiotrophy.
We still don't even really understand why a tiny worm with around 1000 cells (C. elegans) has roughly the same number of genes as a human being. Sure, at the cellular level, the complexity of the two organisms is much the same, but at the macro level, it's not even close. Obviously all the information to build the organism is in the germ cells, but discrete genes are just a part of the equation.
In my opinion, as someone why tries to work this stuff out for a living, we are many years away from grasping how it all fits together. Until then, I'd be wary of modifying myself except in the most dire of circumstances.
We still don't even really understand why a tiny worm with around 1000 cells (C. elegans) has roughly the same number of genes as a human being. Sure, at the cellular level, the complexity of the two organisms is much the same, but at the macro level, it's not even close. Obviously all the information to build the organism is in the germ cells, but discrete genes are just a part of the equation.
In my opinion, as someone why tries to work this stuff out for a living, we are many years away from grasping how it all fits together. Until then, I'd be wary of modifying myself except in the most dire of circumstances.