Paxton Coyote:

I haven't used the Big Agnes Encampment, but I have been using their Lost Ranger 15 for about three or four years now. I'm also using one of BA's 15 degree mattress with my bag. I'm on the "bigger" side (6', 210lbs) and have the "long" version of the bag. I love the system! No more sliding off my ground pad in the middle of the night, plus it is the most comfortable sleep I've ever had camping. The bag/mattress combo even fits into my USGI bivy sack, with room to spare.

I highly recommend Big Agnes. I would definitely recommend that you get the "Long" sized version too.

Take care,