I had a bad experince with a mummy bag last year. Granted it was to short for me, im 6ft 4, but either way i pushed my feet against the end of the bag and feel asleep, temp got to about 10deg and when i woke up you couldnt convince me i had feet any more!!!! it took about 20min for me to regain feeling and by then i was mad at the whole world.
Well this october me and my cousin were working at the big Tulsa gun show and we ran across a dealer selling military supplies. He had some 3 part military sleeping systems for sale. My cousin is a recent Iraqi war vet and lived out of this bag for 65days straight so if he endorsed them who was i to argue. We both bought one and looked forward to giving them a try. now the sleeping system consist of a down filled inner bag, a gore tex liner, and a exterior bivy if im not mistaken.
We headed down to the wichita mountains of OK 2 weeks ago for deer rifle season, yes OK does have a couple of mountains or hills. We headed up to a spot on the mt that i had hunted the year before but we had always spooked deer while walking in during the morning. we figured by staying the nite we could get the drop on them. we decided to leave the tent and use only the sleeping systems for a little test. we headed out with the bag and cabelas sleeping pad sinched to the back of my Gunslinger pack and a mountain house meal for a little dinner. By the way after 10days of mountain house in WY i gotta say they are good but damn im gettin sick of them!!! Anyway we hunted that nite and retreated back to where we decided to sleep.
Temps were only gonna get to the mid 30's so we didnt build any shelter and relied on only the bags. A little campfire, mountain house meals, and a little crown and coke later by the fire and we decided to call her in for the nite. Now ryan, the marine cousin, was well used to sleeping in these packs but i was a little nervous since i hadnt tested mine out yet. he assured me that the trick was not to sleep in my warming layers and instead use my body heat to warm up the bag.
NOW before the jokes start let me tell you we had sperate bags!!!!! this aint broke back mountain okay!!!
Anyway i snuggled in just me and my boxer shorts and settled in for the night. My concern was with fitting since i am 6ft 4 and while not very heavy i have wide shoulders and in my past mummy bag experince this was a problem. Not in the sleeping system, i was snug as could be and was very warm all nite, warm enough in fact that i had to open it up around 3am to cool me down some! and the bivy portion would still secure over my head as well. Also i was able to move around in the bag and even bring my legs up for more comfort which is rare for someone of my length in a mummy style bag.
overall if you have a chance to pick up one of these bags I definantly recommend them,especially for tall guys!!