I've come to the conclusion that I need to convert all my enclosures to front entry. The difference between that and top entry is unmistakable. My top entry snakes are much more skiddish and jumpy. My front entry snakes are for the most part much more calm. If I have a group looking out of their hide in a front entry, I can open it up and everyone stays put or comes out to great me. Coming in from the top and everyone pulls back in until they see what's going on. I think that's the key to this whole thing, they "see" whats going on.
I've tried to let them see me before I come over the top and most will pull back. I think it's just inherent for them to be afraid of things coming at them from the top.
I have noticed this behavior can be trained out of them. I've moved front entry snakes to top entry enclosures and they seem to be fine with that. Granted it wasn't for more than a day at a time. Still, that "somethings trying to get me from above" response wasn't there. Just wondered what everyone else has observed.