Good Bag? MH 1st Dimension +30

Yes, IMHO, it’s light for 30deg F synth bag. What am I comparing with? My Montbell SuperStretch BurrowBag#3 which I consider to be a 30degF bag. The MB SSBB#3 weighs 43oz for a bag that fits to 70″ instead of 72″ for your MtnHW bag.

There are some diffs however. The SuperStretch system adds 2oz to the MB bag (versus the non-SuperStretch version (i.e., Alpine bag). Still, the MB Alpine version would be 41oz.

Now, the question is this: Is the 1st Dimension a legitimate 30deg F bag? I don’t own one, but only ask it since the MB bag has 5more oz of synth insulation than the MtnHw distributed over a shorter length (assume here that we DON’T stretch the bag out more than 60″ shoulder girth – in many cases a reasonable assumption as 59-64″ is a typical number for the shoulder girth of non-stretch bags). If it truly has 4″ of total loft, then it would be spot on for a 30-32deg bag. If we didn’t know the Mfr claimed loft, then, IF we assumed that Delta and XLLoft had comparable thermal efficiencies, then I would estimate it to be approx. a 37degF bag. Given the loft however, this estimate must be incorrect.

Now, maybe Delta is more thermally efficient than the MB proprietary XLLoft insulation, but is it 25% more thermally efficient? That might be a stretch (no-pun intended). Anyone have any opinions or info on this 25% point I’m wondering about? So, at this point I’m confused and a bit skeptical, can the insulating material and construction of the MtnHW be that much superior to these high quality Montbell bags?