How about all that time before the late game when the first corporations become available? And how late is late?
Here are some screenshots from a game of mine:
I was paying 66 gold for 23 hammers in my capital. Do I think that that's a good investment? Looking at the list of recent wonders in the city, yes. And I'm researching Ecology so I believe this qualifies as late game. This is also on Emperor and I was playing on a small map. My research rate was not that bad, despite the fact that I was also paying quite a bit of distance maintenance since I was not running State Property.
A look at the economy overall:
Yes, inflation was a killer, but corporation payments weren't such a great deal. Of course, I didn't spread my corporation like crazy, only doing so in a few cities, but I did have a few Creative Constructions branches in captured cities (a full half of that cost is from them). As a factor of the overall cost, corporation payments were really quite manageable, even though this was late in the game. And the benefits were tangible.
Alright, smartie. That is one thing that looks like it needs some fixing. I was under the impression that State Property abolishes everything that has to do with corporations

Or at least that was the intention.