My personal, but not an informed opinion: Most of the 4.x private servers which promise retail experience are from a leaked official server program. The reason so many suggestions and patch implementations are rejected, because it's a lot harder (or impossible) to modify a closed source code retail grade server, than the custom servers like Not Aion. 4.6 is not that bad, and the overall experience is really good, but there are technical limitations which cannot happen, like patching.