Single or double box for wintering......a 14x12 has more advantages than drawbacks
I am with Ben and Rosti on this.
The main drawback of a 14 x 12, apart from the all-up weight, is that there may be more honey left in the brood box at the harvest. This does not particularly bother me, but it may bother some.
Advantages of:
no frame gap between boxes,
more than enough stores for winter,
extra depth in the box (over a single brood) so the colony can move upwards if there is a very cold spell (like last month!),
no need for fondant early in the winter,
larger box for a more ideal (spherical) brood nest shape,
no restriction on laying space early in the spring build-up,
no extra joints below 'roof-cover' for the winter,
easier to move than a brood+half,
can easily overwinter on ten frames (if necessary),
larger panels for insulation (if fitted),
less likely to swarm early due to brood restriction,
and perhaps a few I have missed.
Other down sides might be:
getting comb drawn as easily and evenly as the deep brood,
having to make a decent frame feeder,
slightly more fragile comb in the frames,
greater chance of breaking a lug on a frame (I use seconds),
getting later nucs up to a full box ( I shall not be troubled with this now I have enough 6 frame polynucs),
needing more thymol for an effective mite knock-down,
big colonies (when they get upset!),
and perhaps a few more.
Overall single brood on 14 x 12 is a resounding plus for me. I am not considering regressing to deep broods in the foreseeable future.
Regards, RAB