So far this year 16 out of 20. Luckily no slimming here. I think 2 never had a queen emerge, I know of 1 queen with messed up wings that i found on the ground in front of the nuc, she flew away and never returned. I lost 1 to swarm that I made a bit too strong and they filled all the comb with nectar/honey. The queen layed for 1 day and then they all left.
The great thing about divided deep queen castles is they share heat during cooler weather in spring, all the equipment is standard and can be easily converted back to a full size hive, also is if you loose the queen, just pull the divider to combine. Just make sure u watch them closely during the flow, they will run out of space quickly.