Hello Andrei,
Well if we get into details we'll figure that things must be quite different for different memory management models. For example Object in ref-counted mode is not a class anymore, it's a struct. So now there's going to be two parts in an app: those in which Object is a class, and those in which Object is a struct. Reconciling those would be a tall order.
I think we *are* taking about different things because that argument doesn't hold for the -nogc I'm thinking of, ref counted objects are still GCed objects, allocating them would also be disallows in a module compiled under -nogc.
Andrei