I have seen the error of my ways, and have just uploaded OIO 3.47 to CPAN which has a "proper" implementation for ->can() and ->isa() that does not rely on cached pointers to UNIVERSAL::can() and UNIVERSAL::isa(). Hopefully, this version will also meet with your needs, as well as with your approval.

Thanks for prodding me to delve into this issue. And thanks again for using OIO.