Mining would be a pain. If you un-burrowed your miners they would mine in each fort interchangeably, and if you put them in burrows, you would have to update the burrows every time they mined a block.
Although it would indeed be somewhat of a pain mining with burrows, it wouldn't be that much of one. You would not need to update burrows every time they mined a block. when designating burrows, you can designate unexplored space as part of the burrow.
Also, I was thinking of doing a multifort of this sort for some time. Maybe even have four or five forts going, or maybe different levels of fort (the kingdom of luxury, the survivalist nation, the poor starving, and the elite military) all more or less self sufficient in different keeps. may include a small outpost in the circus. And may be less self sufficient, with elaborate airlocks for shuffling food/goods around. might actually be helpful to separate the magma industries like this, so they keep on producing masterwork goods during a spiral (for the lowly dwarves to kill each other with.)
This would be a good thread to talk about the various !!science!! elements of it. especially automated or semi-automated airlocks, and whether each fort should have its own vertical column to grow in, or each take up a different horizontal layer (surface, sedimentary mining, cavern(s), magma).
does anyone have a tried and true goods-shuffling-airlock method? or an idea for fully automating it?