Which sleeping combination would be warmer?

[LAMEA-Gals]

Hi there
Planning my next 7 day winter trip to WA and have got the scales out checking my gear - looking for weight savings etc.

I'm a bit stuck on what sleeping combination would be the warmest for the weight. My two options are
Option 1.
- I have a Marmot Atom (550grams, comfortable to about 8 degrees for me), combined with an Exped downmat short (weighing in at 700g). I find the Exped super comfortable and warm but it is bulky and heavy.
Option 2.
- My Western mountaineering ultralite sleeping bag (830grams, comfortable to about 2 degrees for me), combined with a Thermarest 3/4 Prolite (weighing 320grams). The Prolite is OK but not as warm or comfortable as the Exped.

So the question I'm considering is as they are roughly the same weight (100 grams difference) am I better off (in regards to warmth) going for a system with a warm top layer/thin bottom layer or a system with a not so warm top layer but a very warm bottom layer?

I'm expecting single degree temps at night on the walk (probably in the 5 to 9 degree range) - I also am an average sleeper - ie not too warm, not too cold

[Franco]

The performance of a mat has to do with ground and not air temperature.
My guess would be that the Exped will be more comfortable but not noticeably warmer (in WA ) then the Prolite, however the Ultralite will be a lot warmer than the Atom.

[roysta]

Option 2, but keep an eye on the conditions in the days leading up to your departure.
Things can vary from season to season.
If it turns out to be colder there's always Option 3, the Exped with the Ultralite and try to seek weight reductions elsewhere.

[Orion]

The Prolite is OK but not as warm or comfortable as the Exped.

Can you really feel the cold through your Prolite?

[LAMEA-Gals]

The Pro-lite doesn't feel cold but clearly not as comfy as the Exped. The Exped definately feels warmer on any surface I've used it on.

I got a feeling Option 2 is where I'm heading - the bulk of the Exped is a clear disadvantage as I'm aiming to pack 7 days worth of gear/foor into a One Planet Shadow. Also the Western Mountaineering bag has a better temperature range.