I bought a 20" x 66" Rapide-SL pad for my son, and Big Agnes' kids 20* synthetic bag, both secondhand for Christmas. That bag has no insulation on the bottom/middle, relying on the pad for warmth.
He's 8, so I was trying to be very conservative when we used it down to the mid 20's. I put a sheet of mylar-bubble wrap insulation under the pad (like what you would use in a pole-barn) and he slept in sweatpants and a hoody.
No complaints the next day. He said he was warm all night.
As far as comfort, if I didn't mind my feet hanging on the end of the pad, I think I could sleep pretty darn well on his 20x66 pad.
My next pad that I buy will be a 25" Rapide-SL. I'm undecided if I'll settle for the 72" or get the 78" length. (I'm 6')
I have some other pads, including the much praised Thermarest Neoloft. I think the Rapide-SL offers the perfect balance of softness vs. firmness. I've tried it side-by-side in stores, against the Nemo Tensor pads, and find it more comfortable than those as well.