would the all season be hot in the summer?

In NC it could be. I find the summer issue to be more of the non- breathable nature of the pad more than the insulating value. My mattress at home is most likely R20 or more but it breathes.

If you are a side sleeper it becomes less of an issue since you minimize contact with the pad. A nice compromise would be the ul7 syn at 16oz down to freezing and then adding some 1/8 or 1/4 inch ccf for lower temps. In really hot muggy weather I prefer to just lay on the cool ground or 1/4" ccf pad.

"that i might need the 20D nylon Revelation for the extra water-proofing?"

I have a GoLite 20F quilt but have wondered about this. Even if the encapsulating material is 100% cuben, would water vapor still be passable through the seam? And how hard would a cuben quilt be to dry? I'm wondering if it's best to get a synthetic for humid climates with a breathable shell? Skurka did in Alaska... can't imagine going that many days in down without it losing a ton of loft and gaining a ton of moisture weight.