I am going to order an Incubator underquilt in the next few days. I am trying to decide between a zero and 20 degree UQ and wanted some feedback. Also, what affect does the overfill have? I live in Massachusetts and just ordered a Warbonnet Superfly for cold weather hanging in my WBBB. So I ask, what incubator would be recommended and should I get any overfill in it and why.