detail boxes allow recursive detail LODing
this means that a child object of a detail boxed subobject won't be evaluated unless it's parent has passed, so detail that 'belongs' to an object should be made a child of that object.
detail boxes have nothin to do with subsystems in any way, they do not talk to each other, they do not write to each other, they look the other way when they walk past each other in the store, giveing an object that is a subsystem a detail box will not effect it's subsystem status, and makeing a detail boxed subobject a subsystem will not effect it's detail box status.
the box nature of this system has advantages over the radius based LOD system in that you can specify a regon of visability, so if you have detail that is only visable from one side of a ship, you can set up a box that is only on that side of the ship.
if you can avoid drawing two models all the time it would be better to do so, for instance, give a relitively low poly version of the main hull that has a very low detail hanger bay modeled into it, set this model to render when outside it's box, make another version that has a hole were the hanger should be, given a detail box (exactly the same dimentions as the first one) that you should only draw when inside it. in a seperate model (as a child) have a higher poly version of the hanger set it to have a smaller detail box set to only draw while outside the box, as a sibling to this make a highest poly version of the hanger that draws only when inside the box. and as children to the highest poly hanger you can add fighter models and cranes and all sorts of delicious greeble.
keep in mind that detail boxes are in the subobject's frame of reference, so any rotateing submodels will have rotateing detail boxes (this can be worked around by makeing them children of polyless subobjects with a detail box).
and you can give any sort of animated subobjects (this includes turrets and rotateing subobjects)
or groups thereof a detail box.
a shperical equivilant of the detail box, may be available at some point in the near future.
as you can see you can go into rediculus levels of detail with your detail management. have fun
