I had some questionable cells and was out of bottom/top boards, so I tried a stack. It was 2 mediums separated by a QX with cells top and bottom. 3 of them resulted in a laying top box queen, but no bottom box queen signs. Granted, the bottom box cells were a couple days behind the top which may have done them in to start with. One had 2 laying queens, but both were being balled when I took a look. I don't think I'll be doing that again, but it was an interesting trial.
I run 6 medium frames (2 undrawn, 4 resource/brood) in a box with a couple scoops of bees; just enough to control the SHB. To get bees I shake frames into a bin and let them sit for a while, then shake them down in the bin. I'm left with nurse bees that don't migrate back much. I've tried moving frames with bees, but invariably too many go back to the origin hive and the results are spectacularly slimy. My apiary is a 45 minute drive on a good day and most often I have to set it up and walk away for days.
On the last round of queens it looks like a 66% overall mating rate counting my stack experiment. 15 nucs and 10 queens. I'll recheck the missing 5 tomorrow night; it is always possible I overlooked one.