pad/underquilt combo

A pad can add warmth, if you can get it to stay under you.
I've always had problems getting a narrow pad to stay in place, even inside of the two layers of a double layer hammock.

People do use various methods to hold the pad in place, but it would have to be a pad with a good 'R' rating to add noticeable warmth to an underquilt.

My experience with under quilts comes from hammocking in Pennsylvania in temperatures from the upper teens through the 70's. For me the underquilt is the most important component of my sleep insulation. My ratio is just an estimate, but for me I'd say that 70% of my comfort comes from the underquilt with the remaining 30% from my top quilt. It's when the underquilt shifts that I notice a cold spot. I've found I can carry a very light top quilt (I have a BPL UL 60 quilt that I've used down into the low 40's) as long as I have a warm UQ. I've also been known to lay my Montbell Ex Light down jacket over me if I get cold on top.

I tried sleeping on a pad once in the hammock and then tried a second time with a double-layer hammock and found just too many cold spots to be comfortable. Since my first UQ I haven't looked back.

But in my small play time with a Women's XLITE and an underquilt I was extremely hot in not so cold temperatures, I felt more heat on my back with the xlite than without.