That people are leaving the Democrat party at this time shouldn't be surprising. In 2008 lots of people registered Democrat in order to participate in the historic election of the first black president. His reelection is much more ho-hum, not particularly historic.
In 2008 it was "hope and change," in 2012 it is "how has he done?" Sadly for our country, the answer is "not so good."
Most of those leaving the Dems are not registering GOP but either registering Ind or not registering. From a GOP point of view, either works. In 2012 we could have another 2010 "wave;" it wouldn't hurt our feelings.