Almost anyone I know that has a good number of T's use the stack method. That is just how it has to be to conserve space. The kritter keepers work fine because of all the ventilation they provide. Also alot of other containers also provide side ventilations so they are prefectly fine for stacking. Just the way it has to be if your collections are growing rapidly and you are confined to space. No harm in stack-ables etiher. Yes it is slightly a pain for feeding time, but that is the price you pay for that and I don't even think it is a bad price to pay for keeping some elegant looking T's!! I have seen no proof yet that it stresses out the T's at all.
I don't see why it would. Mine seem fine and I've always stacked kks, I have to for the room.
And you can still get plenty of ventilation with them stacked, the entire top and sides have ventilation holes and the have plastic "feet" in the bottom of them, they don't sit directly on top of the one underneath.
When I stack them they fit in my room... If I couldn't stack them, I couldn't have as many tarantulas. But I like stacking things, everything in my room is stacked. I stack movies, books, milk crates, tubs of junk, tubs of crickets... I even stack big bulky stacks of tools (shop vacs and jacks and things) at work. Tetris is my favorite video game, and legos are my favorite toy. I have a thing a fond place in my heart for stacking. If kritter keepers couldn't be stacked and still keep the tarantulas happy, I would never have gotten as in love with tarantulas as I am today.
And, to keep my Avics from webbing the tops closed, I put a piece of meshy tulle cloth stuff over tense between the lid and the container.