i have built plenty off boxes, have tried plenty of different glues, a box that is held together by glue alone, is no better then a prefab box. just tuned different.
and
no, ones the glue dries and you remove the screws you can brake the box easier then if it still had the screws.
another thing that will play a big role in the strength of the glue is how much area does the glue have to hold on to. so the thicker the wood the more area you have for the glue to grab on to the joints, giving the appearance of a stronger box.
like i said that's just how I build them. if you like making them with just glue that's fine.
do you brace your boxes?, or do you think that's a waist of time as well?
my friend used to have a professionally made box "" at a local shop that was not screwed together but had the small nails in and glue.
he wanted a box that would better compliment the subs, which i built for him, when i was done with the install, we kicked the other box apart, very easily.
edit,
the glue was still holding on to the mdf board but the board broke over the glue. and the nails pulled out. if it had been screwed together it would of taken more punishment.