I used the reflector on top of a blue foam pad into the low 30s, and felt a bit clammy on my back. Not sure if it was sweat from being too warm, wearing too many layers, or if it was some minimal amount of condensation. Looking back though, I think the reflector was probably extra.
This afternoon I fell fast asleep using just a blue pad and my mummy bag as a top quilt, temps were mid 40s with light breeze and I felt toasty. Usually I'm a cold sleeper, so maybe you should do some experiments with just the blue pad and see how it goes. The reflector might not be right for you unless you get down into some deeper cold, but you won't know until you try it out in the backyard, where it's safe.