C++ meta classes will primarily be useful for library authors. It is not expected that you have to write them yourself. They can document and enforce some patte

C++ meta classes will primarily be useful for library authors. It is not expected that you have to write them yourself. They can document and enforce some pattern (e.g. an interface) or provide boilerplate that would currently need either macros or, well, boilerplate. But I don't understand what you mean with "an implementation trade-off"?