I'd like to address this bit - posted by CosmicGnosis, attributed to Ieldra
III.1 Outlining the problem
The definitions of organic and synthetic life forms given in I.1 above have some important consequences. Most notably, if you want to add something physical to a synthetic, you can do so with relative ease, since you have the schematic and can selectively change existing parts in order to integrate the new part. If you want to do the same with an organic, you have to redesign the complete organism from the ground up, since every stage of the growth process is affected by the change. Or more to the point: improving synthetics is easy, improving organics is very hard. That's why organics seek to improve themselves with technology, and that's why they create synthetics.
Swapping parts on a synthetic is a bit more complicated than that. Every part of any mechanical system must be designed and developed for compatability. Even in our world today, replacing any part of a whole does not always yield identical results, even if the replacement part used is well within specs. Believe it or not, I have experienced noticable changes in gas mileage from simply changing the brand of oil in my car. And who hasn't come home with a piece of equipment that was a lemon and needed to exchange it for one that works?
We also know that, in MEU, you cannot simply transfer an AI to another quantum bluebox without changing it. The hardware is part and parcel of the whole. Geth are pretty unique in that they can live on a server, transfer to mobile platforms, etc., and apparently remain who they are.
Finally, changes to hardware can necessitate changes to operating systems and other processing algorithms. Unless, of course, you're using Windows plug-n-play - but even then, all of those various device drivers needed to be designed, developed and made available.
On the organic side, we have - genetic modification, cybernetic implants, cloning, growing replacement organs (Dr. Saleon/Heart), other forms of replication (Virmire and Okeer tank-breeding adult Krogan), etc. We also have the Krogan who have evolved redundant organ systems, and both the Krogan and Vorcha can regenerate health - similar, I suppose, to a self-repair subsystem.
It is implied that genetic modifications can be applied and the results take effect immediately. Based on the conversation with Rafael Vargas on Noveria, it sounds like the Alliance buys genetic mod technology to apply to their troops. The genophage was clearly a genetic modification, yet it and its cure took effect immediately.
I won't mention how quickly Reapers are able to manufacture husks, brutes, ravagers, Marauder (Shields - lol), etc. from basic organics. Or their system of converting organics to gray goo.
But I don't think the divide in the ease of modifications to synthetics verus organics is as wide as you've portrayed here, at least not in MEU.