Sleeping systems - advise and insights form the community

[ZQLewis]

I recently moved from a 25mm thermarest to an exped down mat. "Dura" line not the "ultra" range as the ultra line use a lighter range of fabrics. Ok if you had a long big carry for a one off trip.
Cant help re bags. I have an old fairydown/macpac, tapered rectangle down with an early "event" semi waterproof outer. Few years back when I started getting a cold chest back I sent it to twin needle who stripped the down, washed it, added a dwr or hydro phobic coating and added back in an extra 200gr of down.

So I would look for a bag that the down has been given a hydrophobic coating, helps drying in the event it gets wet. 90/10 down, at least 700 loft (measure of expansion/warmth). The weight of down is greater in a larger bag. So probably 700gr may cover you???
Add a silk liner in summer and a micro fiber insulating one if you plan on a really cold trip.
Z