I have a somewhat old Mountain Equipment Voyager II synthetic-filled sleeping bag, that is quite optimistically billed as 3-4 season, although 2-3 would be more accurate. It's still quite comfortable and I use it mainly with a bivvy bag. In its stuff bag it measures about 40cm long x 20 cm diameter and in its compression sack, it is about 28cm long x 20cm diameter. This takes up the best part of a pannier, which always strikes me as quite a lot. From looking round outdoor shops, I get the impression that this size is still not that unusual for 3 season synthetic bags, though I'm turning up some much smaller (apparent) sizes in down sacks in on-line searches. What size and type of sleeping bags are people using on touring these days? Any recommendations for a smaller-packing bag that would do the same job?