I got an email asking about the new sleeping bag with the bivy we are using in the Army now. Since I get to use this stuff at no cost to me in realistic conditions for long periods of time I am in a good position to evaluate it for you folks who would spend their hard earned dollars on it.
Anyway a bit of background. For a long time the Army used these big sucky green sleeping bags. They are equivalent to that big fluffy Coleman brand square sleeping bag we all used as a kid. They work pretty good if you don't have to carry them (they are heavy and very bulky) and they don't get wet (think sponge). Good for a sleep over in your uncles cabin but not for real world use in primitive conditions.
Enter the EWCS modular sleep system. This was a huge update in technology and unlike the MOLLE rucksack they didn't go just part of the way. These things really are a home run. Basically they consist of a light "patrol bag" a heavier bag, a Goretex bivy and a stuff sack. A wooby fits easily into the stuff sack and anybody with an iota of common sense adds one to their personal sleep system. You can mix and match based upon the needs of your upcoming mission/ trip and go with just the light bag, the light bag and the bivy, just the heavy bag or whatever combination suits your fancy. I am very happy that we use these systems at work. I have found them to be rugged, reliable and a great piece of kit. In particular the zippers are quite rugged. I have gotten them hopelessly stuck and through brute force unstuck them without them breaking. Seeing as zippers are a real weak point in sleeping bags this just goes to show the quality and durability of the system.
These things are fairly light, pack up compactly and work really well. The bivy is good for keeping dry unless you are sleeping in standing water or there is a truly torrential downpour. Have a poncho to toss over your backpack/ boots and for traveling light a tent is not needed. With the thin bag and a woobie it is very compact and for me comfortable to 30ish. With the heavy bag I've slept soundly, without waking up freezing in the middle of the night, down into the single digits (F).
[The ratings for sleeping bags seems to have little to do with a comfortable nights sleep and are more about not freezing to death. Kind of like how a 3 foot wide tent is rated to sleep two people (if they REALLY like each other in a grown up sort of way). Knowing if a bag rated to 20 degrees is good to 20 or 30 or even 40 degrees for YOU is something that must be found out for yourself. I don't think this system is good to -10F.]
As for the more nebulous question of if they are worth purchasing for you guys and gals. That depends a lot on the cost. I have seen these systems for sale brand new for a few hundred dollars. At that price it would be a hard sell for me. The camouflage bivy is probably the most important single component. Getting one of them and putting it over a quality mummy bag of any color which you already own that is suited to your area would work fine. If you live in ridiculously cold Alaska or Minnesota then getting a heavier sleeping bag would be a must anyway. However if you look around finding one, just be sure it is in good condition and truly Mil Spec not a far inferior knock off, for under $200 doesn't seem difficult. I found 3 for $150 in under 2 minutes. If you are in the market for a sleeping bag you would be a fool not to buy one of these. To put my money where my mouth is getting a complete one of these systems for each member of our family is in my long plans.