In reply to bedsforsleepypeople:
What do you mean with the greater range of seasons? A bag that is warm enough for winter is surely too warm for hot summer nights. You'd end up lugging a heavy winter bag with you that will also be too hot most of the time!
If you want to have reasonable allround performance at a relatively low weight and pack size, a 600 gram / high quality down bag would be the way to go. Obvious choices would be the Cumulus Panyam 600 and Alpkit Pipedream 600. Both bags weigh in at a kilo, cost you around 250 pound and keep you warm at around -10.
The Alpkit bag uses hydrophobic down, although the shell is made from polyester, while the Cumulus bag uses normal down (hydrophobic is optional at a higher price), but is made from Nylon (Pertex Quantum). In my experience, Pertex Quantum is very silky and drapes nicely around my body to eliminate cold spots. This is a bit less with my Polyester (sea to summit) bag. The advantages of hydrophobic down have also not been very clear to me, since my normal down bag would also cope nicely with small to moderate amounts of moisture.
