Alteknacker wrote: I mention the mattress because, although down is incredibly warm, its insulating properties are dependent upon its bulking; and it can't bulk if you're lying on it, so you need insulation from below.
You're absolutely right about needing a good mat underneath, even more so with a down bag, as the filling is pretty much entirely squashed underneath.
For the record, my winter bag is a PHD Minim 500 thing I got when they were on offer and I felt like treating myself. Still the most expensive piece of outdoor kit I've ever bought! Hopefully, though, I may never have to buy another bag; it should last decades, and it is truly lovely to sleep in when its cold outside, yet weighs under a kilo. I think I'd buy the Alpkit now, as it uses hydrophobic down. Rab and ME bags are also excellent, and a friend has a Cumulus Panyam which looks excellent value.
