Currently my winter pack weighs in about 1kg heavier than my summer weight. This is primarily as I my winter sleeping bag is 0.5kg heavier. Then factor in the extra warm clothing, that eats up the rest of the 1kg. Still, on my ill fated NDW hike, I was kitted out for temps down to -7°C, and my dry pack weight was 7.5kg.
This was also using my slightly heavier camo tarp as I was planning to wild camp in the lowlands, above the tree line where I am less worried, I can get away with my 200g tarp. Tho, in snowy conditions I may start thinking about a more rugged shelter than a tarp.
I want to replace my BA bivvi bag with something a bit lighter, probably an Alpkit Hunka XL, which should get me another 300g. If I could afford to get a down sleeping bag, I would guess I could shed even more weight.
In all of this tho, the real thing that governs the weight is the food. I tend not to go for expensive freeze dried stuff currently, so end up carrying heavy stuff like the LWWF pouchs. A days food is easily 700-1000g.
J