[jbn]

I once used a similar trick combining C++ placement new and multiple classes to mimic several possible values of refcounters to simulate reference counting without a data member (for instance the object is created at C1, AddRef news it in place to C2, then C3, then Release news it again back to C2). When you have only a few possible values of refcounters and the object reuse (for instance if these represent oft-used values) warrants it, this can be used to save memory...