MontBell Plasma 1000 Down Jacket Review

Due to the PNW often living up to its wet reputation, I was slow to convert to down. Seeing that my bargain 550 fill down sweater is 14oz, Costco down vest is in neighborhood of 6-8oz, and my fleece vest is >14oz (sorry for vague numbers/going from memory), I found down to be worth the risk.

My down sweater or vest and sleeping bag stay in a dry bag when I'm hiking. I only bust out the sweater or vest to stay warm during breaks as I rarely need more than a shell and base layer for anything above 20* as long as I'm moving. I wouldn't hike while wearing down due to perspiration issues as you mentioned. If I'm looking at sub-20* temperatures where it's likely that I'll hike with extra insulation on, I'd bring synthetic insulation in lieu of down. I'm a fan of the military style polypro for this purpose but I have a fleece vest too.

Down to even 20 F, I just wear nylon base layer and eVent jacket (and fleece hat, fingerless fleece mittens,…). Definitely have to walk briskly. Carrying a pack uphill I'll stay warm no problem.

When I stop I'll put on synthetic or down vest depending on the temperature.

If for anything, a fleece makes a good layer for stops and breaks in wet weather. When you are wet you cool off much quicker at rest and a fleece won't be affected much at all from putting over damp clothes. Down would get quite damp. Personally I like a fleece vest, very easy to slide on and off.

Another good measure to determine the overall usability of the jacket would be (fill weight * fill power)/ (total weight – fill weight) Lets call this term "shell efficacy"

[The denominator is effectively shell weight + zips etc]

this would be a good mesurement of efficacy of a agreement. For example, a super high fill power low weight garment with very little fill, as alluded to in this article, is not as effective as a slightly heavier garment with much more fill, because, in simplified terms, the garment is not fully utilizing the jackets shell material. This measure is just quantifying this statement. Lets take an extreme example. A jacket with a shell material with 2000 fill power with a shell that weighs half as much as the next shell material on the market would still not be as "effective", using this measure, if it has anything less than 1/4th the fill of the next lightest jacket, even if its absolute weight is lower.

You could even take this a step further and take "shell efficacy"/absolute weight to determine shell efficacy across different weight classes of garments.

I am fairly sure all my math is right, but i'm doing this off the top of my head, so please call me out if my math is wrong.

Best