*Need to check we aren't becoming primitive literals before being ok to include? Seriously? 
You can do ((StandardFileStream >> #primRead:into:startingAt:count:) literalAt: 1) at: 4 put: 34 to achieve the same that become apparently must at all costs guard against, does that mean we should also introduce the same kind of primitive fail check requirements to at:put:?
I get that there are some objects you really don't want to become: due to VM linking them internally in various ways, but checks that apply to *certain instances* of a class, should be unneccessary, imho (or, better, done at the user site)