My experience, larger enclosures DO stress them out. Take Avics for example, they'll web more and be more active in a smaller enclosure vs. a larger one. My G. pulchra started as a 1/2-3/4" sling, in a 4.5" square amac box. Spent almost all of his time under the hide and wouldn't rarely eat. Thought he was in premolt. Stressed the hell out of me (see some of my posts about it ) Few weeks ago the GBB out grew his 2.5" square enclosure so i swapped them, put the pulchra in the 2.5" and the GBB in the 4.5". The G. pulchra has since molted, dug burrows and is now quite the active little T. Even eats regularly. My LP and some of my brachy's are the same way. Upgrade them to to large and they won't eat and just hide all the time. Put them in a more "fitting" size enclosure and they do much better. My rule of thumb is 3 times their DLS. for the width, upgrade them when there's an inch or so left difference in their DLS and width of the enclosure, like a 4" T in a 5" wide enclosure.