I prefer Psr4 because it allows us to add Psr18 when the revised-package thing comes out. With names we might find ourselves in a pickle. Also this stuff doesn't matter so much IMO because it's kind of internal API that not many people are exposed to. If it does end up being Psr5, we'll rename to that. Until the PSR is voted in even if this is merged it can not be considered stable/BC-safe.