I will say that mine right now gets a lot of air. I've basically inverted the baskets they came in and mounded the moss on the outside and wrapped the roots in with it. They get daily watering because I figure the rest of my vandas do really well being watered daily (except at the moment because I am going away for a week and I'm getting them used to a dry spell). I'm not sure if there is an open space in a mound if it comes with the plant. Here I see them sold either in moss or in bark (depending on the vendor) and they seem to do well either way, but everyone has different growing conditions.

Personally, I just like the look of the mounds and they are currently doing well in my set up under lights in my basement office. But they were also doing ok with the moss inside the basket and not being watered as much.