I have the Big Agnes Down 15 deg. bag I think its called Lost Ranger... anyway I got the Big Agnes primarily for the integrated sleeping pad that slides in a pocket of the bottom of the bag, very comfy and eliminates problems of sliding off your pad onto the cold hard ground.
Maybe a few problems to consider, the bottom of those bags have no loft so the sleeping pad is suppose to be the thermal element between you and the ground. If the blow up pad
(which is nice) gets a hole in it you may have an issue if your on a pack trip. My friend had his go flat while we were in a canyon in Utah, there is a little cactus there, luckily it was not very cold at that time, still had to worry about the hard ground. I have not had any problems with mine and you can take a repair kit with you in the field.... just something to consider.
I,m with Oak on this one, synthetic for wet conditions takes the chances out of sleeping in a cold matted bag, I am sure all of us have spent some miserable nights in the field and I am getting too damn old for that. The list of things I won't skimp on keeps getting bigger the older I get... weird