Implications of Cochrane's "Spell Checker" Narrative

As promised in the last post, let's return to the implications of Cochrane's narrative.
For the sake of having a tractable beast to grapple with, I'll summarize it:

Most of the genetic component of whatever capability you have is based not so much on which genetic variants you have, but the number, severity, and positioning of the minor mutations you have accumulated, courtesy of your own insults and the total accrued mutational load of your ancestors.
So, under this narrative, people who are smart for genetic reasons are just less damaged than people who are average, or in some cases, just damaged in different ways.

He therefore says that if we could 'spell-check' a person's genes, that we could expect very significant improvements in their performance in a host of ways.  This would be akin to doing some maintenance and repair to an old ship that is barely running---a lot of low-hanging fruit is probably available for the picking.

Now, in order to implement this sort of thing, we need not just READ capability on genes, which we have at the semi-productized level (PGD screening for single gene defects is available now), but also WRITE capability (and of course, knowing what to write, to spell-check one needs to know how to spell in the first place). 

If this narrative turns out to be the substantively correct one, I don't see any huge insurmountable technological obstacle to implementing it.  One learns what an undamaged copy of gene X variant Y looks like by inspecting lots of different people's versions of it, and you can infer what a pure copy of it should look like, in a similar manner to defect metrology in semiconductor manufacturing development (where if you had a gold copy for comparison, you wouldn't need to do the development in the first place and even once you master the process, you STILL have defects and have to throw away some of the chips you manufacture).

Also, this narrative would tend towards working on existing people in addition to prospective ones.  The only advantage PGD patients would have is the vastly smaller number of cells that would require spell-check.  So this poses questions of when do I cease to be me as well as when do children cease to be 'mine'.

Let's say Cochrane develops a spell checking engine that uses a tailored virus to accomplish damage control---going through your cells and fixing them progressively to the proper spec for whatever genetic variants you happen to have.
Let's stipulate that his technology is good enough that you experience around a 10% improvement in general functioning, by taking out a reasonable amount of the trash that you've accumulated.  Are you still you?  Maybe you can run a 40 yard dash a little faster and you're somewhat healthier with a few years more expected lifespan, and improvements in your brain are on the order of 5 points of IQ or so.

I'm inclined to say, yes---with the hedge that at some point, quantitative improvements take on a qualitative character.  People who have major dysfunctions corrected---for instance, thyroid regulation---often experience greater effects than these and I've not seen them lament that they are not 'Themselves' anymore, nor have I heard such reports from those around them.
I'd be less confident if the improvements were much larger though---for instance, say a person went from the equivalent of an 70 IQ to a 160 IQ---would anyone recognize them?  Would they recognize themselves?  Would their soul depart and be replaced by another?  At this point, we just don't know.  This is far outside of our realm of experience.  The insights gained from this research tread on theological as well as scientific grounds.  Is the idealized version of you still you?
Looking at the PGD case, it raises the question, is the idealized version of your son still your son?

Being a reactionary Christian, I don't honestly worry terribly much about this, as God has already promised me an even more idealized version of my body post-resurrection than Cochrane could ever hope to deliver and assured me that it will still be me, just more so.  So technology which simply hopes to repair some of the effects of the degradation post-Fall hardly threatens me.

But for a hint as to what sort of opposition that said technology would encounter if this is the correct narrative (in question) and should it be developed and productized (almost certainly if the first premise is true), I invite you to ask the question....who....whom.
I'm sure the Second Sigma, for instance, would gin up all sorts of reasons that the protocol is evil if it looked likely to reduce their effective advantages and position in society.  I'm also certain that the usual suspects in love with Death (and frequently also, with Sin who is the mother of it), would find reason to howl at the prospect of even a 10 year extension of average maximum lifespans.
Let them howl, should the center hold, their sound and fury will signify nothing.  Betting on a technology not being developed and used when the prerequisites are present is, IMO, a fool's wager.