In regards to biological evolution, the issue is how many of the positive effects are inheritable.
Crispr is out there but from what I've read, our genome is so complex, predicting inheritable changes is sketchy.
As to other enhancements.
Most of the mods seem more a temporary upgrade that end with death rather than bio-evolutionary events.
The pressures of natural selection in humans already has tilted to the 'un-natural' as our intellect becomes a prevailing influence in selectivity.
Selectivity goes beyond the influence of the environment as humanity alters the environment in seeking success as a species.
With Transhumanism, change is focused on the individual.
The need for inheritable change becomes less relevant.
The possibility for evolutionary stagnation and even minor de-evolutionary trends becomes a problem.
A social problem. Who will be allowed to procreate?
And there is the issue of elitism and class struggle. Not everyone will have the financial ability for the upgrades while it will be the upgrades that favor wealth creation intensifying class divergence.
And of course, there will be the military's dark interests in devising generations of super soldiers.
With 'baby steps' most of the above won't be perceived until there are social problems.
Maybe 50 to 100+ years from now, socially, more of course on the biological angle. Many generations.
There will likely be many positives initially, but humanity isn't all that altruistic.
Someone usually figures out how to leverage a good idea for selfish reasons.
Resistance is futile.
'It's what we do'