That kind of local class alteration is very different from the kind of tricks done in OSGi. In OSGi a class is the same no matter what context you're in, it's j

That kind of local class alteration is very different from the kind of tricks done in OSGi. In OSGi a class is the same no matter what context you're in, it's just that the context you're in affects the look up from class name to class. So all the caching or optimisations you might do against classes are still valid. Refinements mean things like method lookup are sensitive to the context and become much more fun.