My current fort has been running for 4 years. All the male dwarves are both in the military and armed purely with a spear, a copper shield, then leather cloaks, leggings and boots. I do not use danger rooms. To date I have had 5 forgotten beasts attack the fort (none of them 'liquid' ones), 3 ambushes (one of which was elven - I was really quite pleased to embark at war with them), and a siege.
I have lost 2 of my "dwarf spartans" so far. They run around naked, with spears. Naked. With spears. One of them single handedly took down a forgotten beast with a copper spear he'd named earlier (admittedly that dwarf was a spear master at this stage). The worst injury sustained so far whilst the dwarf remains alive is a lower right arm having been scratched off by another of the forgotten beasts. The fellow vomitted all the way to his room, rested for about a day, then got out and started sparring again. Later he killed a forgotten beast himself (though with help).
The point is this - the idea that a danger room is in any way a requirement compared to regular training is ridiculous. It totally ruins the Fun, and at this stage in the fort I'm becoming rather adamant that armour too is a Fun ruiner.
I did this too - Except with added helot population. The ensuing fun was to be had when - Yes just like history, the biggest danger to me was the Helot population. I made them unhappy as hell, and they frequently tried escaping from their
DESIGNATED LIVING AREA only to be caught and placed in my uberena. Same with captured enemies.
And my sparta dorves.
*It died in the happiest way possible - MASS REBELLION. Spartans won.
Then they starved.