For the most part the optimization works well. The more subtle issue is that the union trick used by the endian utilities is not compatible with constexpr expressions. There are some interesting use cases for constexpr serialization that fail if the conversions are interposed in the Reader/Writer types. The alternative is to use reinterpret_cast, which is also incompatible with constexpr expressions.
Moreover, endian conversion templates are unusually frustrating in the current C++ standard. I wish there were a better way, but one does not currently exist.
Moreover, endian conversion templates are unusually frustrating in the current C++ standard. I wish there were a better way, but one does not currently exist.