Back in 40d, I decided to try another approach to dealing with migrants. After the fort hit 20 dwarves, I put my plans to motion and the "Right for Passage" hallway kicked in.
Simply put, it was just a platform disconnected from the fort with a drawbridge. Any migrants that arrived from then on were put to squads, and ordered to spar on the platform. Which had a 10+ level drop below it.
The dwarf who survived the melee was let in.
Was amusing, to say at the least. Also put a lot of marriages at test.
The only one who ever was upset about seeing someone die though was a kid but she got over the whole "MY PARENTS ARE DEEEEEEEEEEEEEAD" in a while.
Not as evil is the second thing, also back in 40d. I separated my fort from the sweatshop area. It was just a huge room dug in loam, with about thirty beds, some tables and chairs, and workshops everywhere. Migrants moved in, they go there and start working. I had to move the butcher shop to a secured location after a tantrum spiral started to arrive, but things got under control before it escalated too much.
Anyone who made an artifact though was given passage to the real fort, sealed with two bridges, where my original 7 lived in Royal bedrooms, having the luxury of the finest of alcohol and food. There was a brewer/chef among 'em so they always had the best chow there was.
The other side? They ate plump helmets and drank from a well.
Then one day a skeletal super-dragon showed up, was playing with some mod, forgot what it exactly was, but it ended up killing all the soldiers, scorched the fields and killed all but a few dwarves before it ended up caught in the fire and turning to ash. The survivors didn't last long though.
Eventually abandoned that game. The continuing assaults from enemies were taking their toll on the newly recruited militia, even with the decent gear they had. But at least some people on that fort were extremely happy. Should do this sort of set-up again in the new version. A lot easier too thanks to burrows.