I'm a back sleeper so the mummy shaped pad doesn't cause any issue to me, whether or not I've stuffed the pad into the sleeping bag. I also uses the Airmate lite 5, and i find that the pack size of WinterLite 9 is not a lot larger than the Airmate lite 5, but it's a lot warmer. I can use a lesser duty sleeping bag with the WinterLite 9.
This review was written in the old system and had content requirements that are different than reviews written today.