I received my shamu IX underquilt last week from Tree to Tree trail gear and finally had a chance to test it out last night. Temps were ~39 degrees and I was TOASTY warm. I had my 25 degree sleeping bag as my top quilt and slept in only my long johns. The quilt fit me as snug as a bug in a rug I am amazed at how warm it keeps me given it's size and weight. Man, this insultex is really powerful stuff.
Hat's off to you Mac for creating such a great product. Anyone who is on the fence about getting a Shamu--PULL THE DARN TRIGGER ALREADY--You won't regret it! Also, Dale over at Tree to Tree trail gear was awesome. I had originally ordered the Universal IX UQ (which is retired) but due to a snafu in the TTTG shopping cart, I was able to place the order. Dale sent me the shamu at no additional cost because of the error--talk about great customer service!! I am glad he did, because this baby is sweet! I will order all my gear from him going forward if they have what I am looking for.
I am headed out on a backpacking trip into the superstitions this weekend and temps are supposed to get into the low 30's. With my new Shamu, I know I will sleep comfortably