I've used the issue sleeping bag a lot, but found myself leaning towards a Softy 9 instead, or even an issue tropical bag (Herrick/Telic issue) in summer. The issue bag is warm and that is great, but it just takes up a heck of a lot of room in your bergen... Ideal if you have a vehicle or are static though! The tropic bag is also good as an indoors sleeping bag for those who find themselves gonking on their mates floor or wherever else, packs down nice and small and you can get a washable liner for it, very convenient.
Recently though my Softy 9 bag has become pretty clapped out and I've just gotten an American issue sleep system, its modular and 3-in-1, a summer sleeping bag, a winter sleeping bag and an MVP bivvybag that you can use separately or all buttoned together depending on if its redders or bloody Baltic out. Not bad, I can't imagine you would get a modular new civvy system thats goretex and rated for down to -50F
for £100. Its big when all 3 are buttoned together but thats only to be expected - less bulk when only 1 bag and the bivvy are used. I'll let you know how it does once I put it to a proper field trial
I would certainly consider the American one if you are after a winter sleeping bag...
If any of you know Jasper at Strikeforce supplies, he can sort you out with the American bags, and the trop one too for about 20 notes, and their service to me has always been very good. I don't think he has any Brit issue GS bags listed though, but you can always ask, he's quite a helpful chap. You might also try UK Kit monster, they often have stuff like this too, as well as the issue inflatable mats, at a lot more reasonable price than a thermarest!
