In a sense my 'nation-states moved to orbital colonies and an Alpha Centauri world' vs. Pharmabanks setup presents similar issues- I have them more as coequal though since ultimately through desperation and guns nations still 'know where the megacorps live' and retain naval and expeditionary power as an ultimate veto to access to markets if nothing else, and seizure of wealth in a showdown.
But the nations did sign away large assets to 'buy' cooperation in staving off The Plague, including the Earth's biological diversity itself and pretty much all explored world's biotemplates, thus monopolizing most biotech to the pharmabanks at a nexus of medical, industrial and financial power that undercuts national authority.
I'm gathering though that the OP's Universe doesn't have any one corporate type have quite that much power- more diffused and counterbalancing/competitive but ubiquitous.
Here you have more varied types of corporations - one doing biotech, indeed, but another one is primarily into mining, another into agribusiness (and terraformation), and the fourth deals with general exploration and colonization.
Big difference is my limited expansion vs. a more open rapid interstellar expansion. If the latter is allowed, you can expect more 'corporate colonies' and more of a 'captured' populace brought up in the megacorps system. Depending on the 'personnel policy', that might mean very loyal employees or very resentful populations that would look to a nation for redress- or rebel to make their own...
Yes, here expansion is quite fast. Approximately 25-30 years per "generation". So many corporate colonies ala Outland/Aliens.
Larger colonies also attract a large unofficial colony - people fleeing the hell of Earth for a "better" life in the colonies, living in shanty town around the main colonies on the open-air worlds or in old mine shafts in the inhospitable rockballs and working temporary jobs. Arriving by Low Passage - some do not make it. A successful colony will attract a huge unofficial population, in a "gold rush" manner. Corporations tolerate this as it allows for cheaper labor in the lower-end jobs.
I guess the other parallel I see with this latest installment is that my Cloud is something like his Wilds, but I'm wondering if he has considered using it the way I am- strange societies, secrets, source of illegal weapons/drugs/research including deniable activities/labs by the corps, etc.
The Wilds on Earth are indeed available for all sorts of secret activities, though this is dangerous, as the environment is hostile and often so is the local population.
The main source of illegal drugs and weapons is the Blight - ravaged urban sprawl outside the arcoblocks. Little or no policing; tenuous government control; gangs rule supreme.
Given his definition, I might consider SOC to indicate how far up the Corps/Bloc feeding chain the character is. Below 6, out in the Wilds, maybe has to have a work permit (temporary) to even do starship jobs.
Yes, 9+ is arcology or city center; 5-8 is Blight; and 4- is Wilds.
Off-world colonists could be of any SOC.
I'll eventually write a "Salaryman" career available for those of SOC 9+ only, with easy Qualification for them... Arcology "suit drones".
People from the Wilds and the Blight will risk Low Berth travel - with a risk of death - to get off Earth and to a (relatively) better life in the Colonies.