I don't own the Robens sleeping bag but slept surely 600 to 800 nights in the Snugpak Special Forces 1, usually in conjunction with the Snugpak Special Forces bivvy bag. The bivvy bag works very well with the SF1 and is outstanding light.
The Robens is a summer sleeping bag, the SF1 a 3 seasons sleeping bag for the advanced user.
The Robens seems to be sewn through, what causes heat loss at these seams.
It's recommended down to 10°C. That's approximately what you have tonight in your town. We still have high summer, isn't it?
The SF1 is constructed for lower temperatures, they use a Swiss made filling, that can be compressed very well. The packing size they tell you means a fully compressed bag. The compression bag that comes with it is a bit small for my taste. I carry SF1 and SF bivvy bag together in a 7 litres Ortlieb PS 10 dry bag, compressed into it by hand. That is handy and works very well. Of course the package is in the end far smaller than 7 litres, but the sack has that size because that's the most handy solution.
They use a heat reflectiv fabric inside. Thats a third, from outside invisible layer. Surely a reason for a slightly higher weight but far smaller packing size compared to products of the competition with the same temperature rating.
The Special Forces System is the top model of the Snugpack sleeping bag offers.
The SF2 goes into the SF1 if you zipp in the adapter and both together fit into the SF bivvy bag.
It's always large enough to wear additional clothing in it, it has a totally different cut than the narrow Robens.
That's a military sleep system that allows you to wear a complete winter uniform including boots in the sleep system. It isn't called Special Forces without a reason. No idea if it's issued somewhere, but it's obviously developed for military use and has a NATO stock number.
Such stuff is robust, pretty idiot proof and long lasting.
The zippers don't lock like at the Robens. NATO sleeping bags have well resting zipper sledges that you can open in panic how you want. You can just pull the sides of the sleeping bag and the zipper opens.
The SF system is thought through like that in every point and if you want to compare it with something else, you should compare it with Carinthia Defence1 or Carinthia Tropen + Defence 4 and Carinthia GoreTex sleeping bag cover or the US army equivalent. Like that you compare the real competitors, not a Vauxhall with a Porsche.
To make it short: The Robens is not well insulating enough for British weather conditions. The colour would blend well in south French or Italian summer conditions where for it is obviously constructed.
The SF 1 is exactly made for British weather conditions during the warmer month. The SF2 for the colder month. Both together for the lowest temperatures that are realistic to assume in Britain, especially if you wear additional Ullfrotte's Woolpower underwear and a padded military winter suit, how it's issued in NATO armies.
If you buy the complete SF system you pay two sleeping bags but get options for using that as if you would buy three civil sleeping bags. In extremely cold conditions it's heavier than a civil winter sleeping bag but far more comfortable, because you can regulate the heat very well.
As you surely don't go so often for camping at -20 °C, the option to put one bag into the other is nice to have, but not the main reason to buy these sleeping bags.
But if you already start to invest money, I recommend to keep every option open and get the right stuff from the beginning.
The SF1 is the lightweight 3 seasons part of the best sleep system that you can get for civil use.
The Carinthia system Tropen + Defence 4 is a bit more practical to use but a bit less comfortable in winter conditions.
The Carinthia Goretex sleeping bag cover is much more expensive and much heavier than the Snugpak SF bivvy bag.
As the 3 seasons / summer bag and the bivvy bag is what civil users use most of the time, the lighter and cheaper Snugpak SF version is the better option for recreational use and most people who have to pay it themselves.
Another little but important point is that if you sleep without tarp in the bivvy in the open in the rain, you have to roll in the Snugpak SF system onto your left side, where most people fall better asleep.
Carinthia puts the soldier who sleeps next to the front line in the open field onto his right side, because that has an important influence on heavily stressed persons.
If you try it out in your own bed, you will see, that you fall on the left easier asleep than on the right, unless you have for good reasons psychological problems.
(You could of course use a British military bivvy bag as well, that has no zipper flap that forces you onto one side if you sleep in the rain. For the international market this model wouldn't be a good idea, because you can't ventilate it enough for use in central Europe or areas with similar weather. The British army bivvy bag weighs approximately the double as the SF bivvy bag.)
The Carinthia system is the more robust and over all slightly better system, especially regarding the bivvy bag, but much more expensive and a bit heavier.
For civil use the Snugpak SF System is in my opinion the best that you can buy on the world market.
I don't own that Robens but I can tell you that the Snugpak SF1 in it's bivvy bag is very convincing to use everywhere between Biarritz and Usedom from March to November. If It's cold I simply wear the clothing of the day without waterproofs in the sleeping bag and it's fine for me.
I am used to work, live and sleep outdoors. People who rather live and work in heated rooms can use the SF1 in it's bivvy bag on a good mat, let's say the British army roll mat, perhaps until 5 °C in a merino wool or polyesterfleece suit.
But I rather recommend to invest additional into a padded suit, for example UK made by Snugpak or something from Carinthia, and a second pair of warm socks, than into the SF2 if you don't plan to go for camping below the freezing point.
Some more informations about that I wrote in this thread:
Greetings from Orlando, FL USA! This is my first post and I'm looking forward to input from those of you across the pond with presumably greater access to UK military gear (although I'm working on acquiring some). I'm aware that the recent British lightweight bag was apparently inspired by the...
bushcraftuk.com
