Testing it during this year's (2013) Keswick Mountain Festival in mid May it performed just as you'd hope when you know you're a hundred miles from home for several days. After using down for so long it took time to adjust, mentally, to a sleeping bag with so little loft providing sufficient warmth as the temperature dropped close to the comfort level, but it provided 3 consecutive unbroken nights of good quality sleep.
The thing with good sleeping bags is you don't really notice what's particularly good, you just sleep, and that was the case with the Montana 2. The draft collar was a bit smaller than expected, particularly having just emerged from a winter with down bags, but together with the very comfortable ergonomic foot box and OTI filling it kept the cold at bay with no cold spots anywhere.

The hood is functional rather than luxurious but again does its job quietly without any fuss and works particularly well with Mammut's inflatable pillow.
It's hard to see where sysnthetic sleeping bags will go with hydrophobic down now becoming widely available, the achilles heel of down when wet has always been the main reason for synthetic insulation in bags and synthetic bags are always heavier are bulkier than a similar level of down bag. Although alone in the luxury of a 2 man F10 Vortex one obvious feature of the Mammut Montana 2 was how thi the bag is compared to down bags, and I instantly wished I'd had it available while testing hooped bivy bags from Rab and Terra Nova. Where a down bag lofts to fill the available space, running the risk of collecting condensation through contact with the bivvy skin, the Montana 2 would give the same insulation but only half fill the available height...if that.
At £80 (£60 with a GoOutdoors Discount Card...and it's exclusive to GoOutdoors) it's a good value bag for 2 season use. It's simple, durable and performs to its quoted comfort level faultlessly. The option to freshen it up with a 60° wash cycle at home will help it last for years without high maintenance costs and while hydrophobic down may be increasingly dominant in the 4 season market synthetic bags provide an affordable option in the 2 and 3 season sectors.

Price: £80

Weight: 950g

Colour: Smoke-Black

Features:

•OTI™ Element synthetic filling offers great warmth to weight ratio
•Balance™ outer fabric, SoftTX™ inner fabric
•Seamless construction avoids the formation of cold spots, improving insulation
•Ergonomic foot gives you extra comfort
•Machine washable at 60°
•Ajungilak® Comfort Technology

Pros: Small and lightweight for a synthetic bag of this rating. Synthetic filling provides reliable insulation even when wet. Low loft makes it particularly suited to use in restricted space such as bivvies. Machine washable

Cons: