I had a chance to test my summer Phoenix (1 oz overstuff) this weekend at the hang with HamMike and CrackedUp at Symmes Creek trail in Wayne National forest. This was my first hang in my new bridge hammock and the first night I found that I would need to add a center support to make the quilt work with the bridge. (Remember: Always test at home first.) That night I had to make do with large foot pad under me. It worked, but not comfortably. The temperatures dropped to mid-30's.
The second night I had made a duct tape and shock cord center support running up over my ridge line. You can see it here:
That night the temperature dropped to a cool 32 degrees. The summer quilt is rated at 40, so I figure I was stretching the rating a bit. It kept me warm enough to get a nights sleep. I don't think there was ever a time when some part of me didn't feel cool, but I never felt really cold either.
Bottom line: I bought this to use when the temperature is supposed to be above 50 degrees, figuring the extra 10 degrees would be nice insurance. Knowing I can get through the night comfortably enough to sleep if the temperature should drop down to freezing is a real comfort. Keep up the good work Stormcrow. Its amazing what you can do with 5 oz of down!