Instead of orebfusicator that changes every stone and dirt to ore why not drastically reduce the number of changes and turn each ore to stone until revealed like what orebfusicator does. Less lag, no X-raying ores. My understanding is that you can do this without altering blocks in the world files with the same effects as to keeping people not able to reverse the effects as it is server-side.
Edit: Im not sure if there is another engine mode of orebfusicator that does this or if it would have to be a different plugin