Last years Doctor Who Christmas Episode drew more viewers than this years (2011 8.9million, 2010 10.3million) although all programs on TV had less viewers overall, here. If the Harvesters where replaced by the Yeti, would Doctor Who have more viewers? I believe so as a lot of clssic fans would tune in, and it wouldn't have involved a massive rewrite either!
Although I Really enjoyed this Christmases Doctor Who, I found the Harvesters to be quite poor, possibly the most pointless part of the story, and they could have been replaced by so many classic monsters with a quick rewrite, even though bringing back most monsters means paying the creator, I'm sure it could have been done!
Heres hoping next Christmas isn't down again, and the link between snow and a monster isn't that hard for Moffat to make!
Snow-Yeti - Obvious
Snow-Ice Warriors - Obvious
Snow-Harversters - Huh?