I think the anti-perching holes on the side are genius. But when you say "vapor block" on the top, are you referring to those tiles I can see in your photo? Does it matter if they are glazed or unglazed (assuming they are actually tiles)?
Like many in this thread, I am going nuts trying to figure out what to do with these yang mei trees. I only have two and don't want to kill them. Out of desperation, as soon as I got them yesterday, I soaked them for a couple of hours in filtered water, then potted them up with cactus mix lightened with perlite. With further research I suspect I may be moving them to something more, um, sterile. I know some of the SoCal crew are going with horticultural sand, horticultural charcoal and rice hulls or vermiculite; but I don't know if that is just to get the little guys over their jet lag or what.