on a related note, the redbrookhoney site that comes up next if you click on the video clip (on youtube rather than the embedded) has a nice clip of 2 nucs being maintained over winter over a strong double box colony ([ame]http://www.youtube.com/watch?v=ZXDZ3RdSxME&feature=related[/ame]).
my only modification would be to use a divided snelgrove/wedmore board to provide entrances and double screened connection with brood below.