I have a Reactor. I think the temp. rating is optimistic. On the ground in my Nemo Meta 2P with both vestibules open and 7 to 15 mph winds blowing most of the night, I rode the temprature down to 30* wearing fleece hat, fleece gloves, Patagonia Cap 3 thermals, heavy hiking socks (that I will not hike in), in a Mountian Hardwear Lamina 45* with Reactor on a Thermarest NeoAir. I slept reasonably well, not toasty. I would have been more comfortable in 20 degree bag.
I was going to see if I could make it down to 20*. One night the temp was headed to 24* and I thought, close enough. I just could not get myself out there to run the test. I think it was that little voice of reason inside my head that said, "you already found your limit with that set-up stupid".