UQP's change the layer where the frost develops. The moisture goes throught the quilt and the frost will be on the UQP rather than the UQ. It's a nice plus.
In regards to the cold spots, if you think everything is snugged up is there a chance you have it too tight? Remember too tight can have the UQ pulled
up without being able to settle down with your weight. Your weight/hammock push into the UQ and cause compression of the down and a spot where cold
can be felt through the inadequate loft. Just a thought.