Personally I haven't found any benefit to using a backstop. It doesn't seem to make much difference the way a nuc vs. full deep does. Don't ask me why, but it just doesn't seem to matter much. I think it has to do with the fact that you aren't using foundation, and so the bees aren't patrolling several layers of unused foundation, they just have to patrol the walls close to the cluster. The farther from the cluster you get, the less bees you see and sometimes none at the very back.
Scot Mc Pherson<br />McPherson Family Honey Farms<br />Davenport, IA<br />BeeWiki: <a href=\"http://beewiki.linuxfromscratch.org\" target=\"_blank\">http://beewiki.linuxfromscratch.org</a> <br /><br />Pics:<br /> <a href=\"http://linuxfromscratch.org/~scot/pics/bees/\" target=\"_blank\">http://linuxfromscratch.org/~scot/pics/bees/</a>