buying new sleeping bag

[tassie kate]

Overland track May 28th till June 3rd

tossing up weather to get a new sleeping bag or not. My current one is about 10-15 years old(handed down from dad), its a mountain designs tapered bag with a hood and its 100% down fill. I can not find any tags on it saying what it's rated too or the model. It lives in my swag and I've never had a cold nights sleep in it. I'm planning on sleeping in thermals/beanie and down jacket and fleece pants if need be. I've also got a S2S thermalplus liner. I've put it in a compression bag and weighed it 1.8kg.

I am tossing up weather I should buy a different sleeping bag that weighs a lot less (hoping for around the kilo mark) and one that i'll actually know the rating off.
My sleeping mat it the exped winterlite synmat, R-value 4.9.

So far I've been impressed by MONT brand
http://www.mont.com.au/helium-450-lhz-1 (comfort rated -1 for women, -7 for men, 800+ loft, 800g)
http://www.mont.com.au/helium-600-lhz-1 (comfort rated -4 for women, -10 for men, 800+ loft, 950g)

Pros/cons/suggestions?

[Hermione]

They are both reasonably lightweight bags by the look of it. I would choose the Helium 600 because I'm a very cold sleeper but you might be different, my 600g fill sleeping bag (not a Mont) is warm enough for winter in Tasmania. They are made of much lighter fabric than your current one probably is, so that might be a consideration depending how much abuse you subject your gear to. The plus side of that is they weigh half as much and will take up a lot less room in your pack. There are lots of similar sleeping bags to choose from these days, I think it's about deciding how much down fill you need for your intended use and how warm/cold you sleep, how much your prepared to spend and what's readily available locally (unless you order online from overseas, not great the moment in terms of the dollar).

[north-north-west]

Mont make very good gear, which is designed for Australian conditions. I have one of their older bags and it's very warm (although it doesn't get much use since I got the ApII).

One of those would be perfectly adequate given the rest of your gear. Like Hermione, of the two I lean to the 600 - it's better to have a warmer bag and remove clothing than to be too cold for comfort.

You might also want to have a look at the S2S bags. They use 900+ down and the bags are well made.

[stry]

The revamped One Planet range is well worth a look. Good products at fair and competitive prices.