Personally I like the headspace, and my BPs seem to as well. I've had several now that I purchased that never saw anything taller or larger than a CB70 tub. Those max out at about 6" high. I have some smaller BPs that are in ExoTerra glass cages. I love these BTW, but they are harder to maintain proper humidity levels. Those that had the higher head space always seemed to use it. Usually they'll explore it and some even climb a bit. When it really shines though is feeding time. It seems the pythons have a natural inclination to use gravity to let the prey slide down making meal time a bit easier. When I was building my first set of display enclosures I kept thinking about this and what I would like to look at as well as how to maximize space. I settled on 14" of interior height. I'm not saying all keepers need that amount, but I can say that my BPs use it to their advantage. Of course on the flip side, I do have tubs as well and everyone in them does just fine. I think it all comes down to personal preference. 14" for display and 6" for keeping is where I ended up.
Reading this back I'm not sure it answers anything now.Just my observations. I doubt 14" or even higher would stress a BP. The tops are covered and or opaque. Nothings going to come at them from above. I'm willing to bet they know that.
Dave