It is my guess (though I have no proof) that most places with particularly large repositories have lots of binary files in them. It's hard to get a 15GB repository if you just have text.
This sort of thing suggests a centralized check-in/check-out model, because binary files are difficult to merge sensibly, and nobody wants to spend terabytes of hard drive space storing the repository locally. And your centralized check-in/check-out needs, whatever scale they might be, are probably tolerably well served by one of the existing solutions.
Yes, but why is that a show stopper? It's a small market filled only with people who typically have large fist-fulls of cash and are dependent on version control. It's a small market, but companies in it have the resources for a good solution.
Because those companies generally already pay the $$$ for Perforce (which has any number of deeply terrifying, shiny red candylike self destruct buttons and makes git's user interface look kind) which for all its other faults handles this specific user case extremely well.
It is my guess (though I have no proof) that most places with particularly large repositories have lots of binary files in them. It's hard to get a 15GB repository if you just have text.
This sort of thing suggests a centralized check-in/check-out model, because binary files are difficult to merge sensibly, and nobody wants to spend terabytes of hard drive space storing the repository locally. And your centralized check-in/check-out needs, whatever scale they might be, are probably tolerably well served by one of the existing solutions.