I get 70-80% acceptance of started cells on a regular basis, and have had as high as 90% many times ( start to finish ).
Here is a picture of my cloake board; I use this to easily switch the hive from queen-less to queen right.
Here is an excellent link that describes how to use a cloake...
I build my nucs with lots of space on the bottom. When I do my hive inspections and find frames with swarm cells on the bottom I just drop them into the nuc boxes. I don't worry about the cell getting damaged on the bottom of the box because I've made them with lots of room.