I would have to say in my very limited experience that I prefer vivariums. I just can't think they would be as happy in a rack system as a really well done viv with lots of room to roam. Granted my two snakes prefer to remain fairly sedentary. Except for feeding time of course when they go wild after each bite. But that's just my humble opinion. And James, I love your viv wall. That's a very impressive and very well done construction!