I decided for the first time in all my forts to train up a Marksdwarf Squad. Built my upper fortress around this concept. It actually came out looking much like a three tiered version of the standard fortresses main floor to a point. The main floor was raised up two z-levels. I had alternating fortifications and walls along with two entrance gates. Trained up my usual squads of 8 axedwarves, 8 hammerdwarves along with 8 marksdwarves.
My First siege of goblinite decided to show up after some much do "encouragement" on my part [they where busy being at peace with us due to being so preoccupied with being at war with everyone but us. So I "fixed" that with some active "tourism" after some relatively boring starting years.] Set all my squads to guard the first floor and close the gates. Only I got to watch a little over half of my marksdwarves [the others finding every plausible task to evade their station order from, collecting ammo one bolt at a time, to praying to the deity of darkness and plants.] offensively dodge towards the one goblin crossbowman's fire falling down two z-levels to face all fourty invading goblins one dwarf at a time.
I still haven't tested out my wall grating plus fortification remodel in favor of my highly effective normal squad layout along with all my other tiny projects... I realize why movies didn't use marksdwarves...