Pete Jensen wrote an answer about Marmot Trestles 0 Sleeping Bag: 0 Degree Spirafil on January 24, 2011
I can't help but wonder if this is all a matter of technique. I work at an outdoor shop and I see more than a few people try to roll a bag and then cram the roll into the stuff sack. That would be the wrong approach, and when I show them that they can just stuff it in the STUFFsack in short order... Well, I get all sorts of different reactions.
From my experience with Marmot bags, it's a tight fit, but it's not that hard. You can also look into other stuff sack options, I use a Sea to Summit Dry Comp bag for my down filled back, and I can really compress it much better than just the stuff sack.