So I recently picked up a 2QZQ under quilt protector and I feel this is almost a necessary gear item. This will help anyone who's ever experienced cold spots or drafts. I see all sorts of suggestions, (snug it up, loosen it, more towards the feet, towards the shoulders, move the down, etc). All my problems were fixed with an uqp.
We ask for our under quilts to be light weight and they are but they don't do a good job of blocking the wind. (I use a hammock gear 20 degree under quilt for reference).
On a recent trip, temps were around 50 in the morning and I was hot to warm. I dropped of the uqp and instantly felt a little chilly.
I know it stinks to spend an extra $50 on an already expensive set-up but it my opinion they are well worth it.
Anyways, it really helped me a lot and for anyone else experiencing cold spots I suggest you try it.