how is this compared to the marmot greenland down jacket? Am 6'2" at 160lbs., 32' waistline with long arms, do you suggest a L or an XL?

Correction: fill power is rating of the amount of loft in a given MASS of down feathers -- not a given volume. Loft = volume. Therefore higher fill power means lower density, a good thing, because this means the same amount of puffiness can be had with less weight.

slisn. First off, I would consider getting an XL because of your height. Secondly, I think you will find the XL to accommodate better the length of your arms although it may be a little more roomy in the chest. There are two main differences between the Sub Zero SL Jacket and the Marmot Jacket. First, Marmot uses an 800-fill power down in their jacket and the Sub Zero SL utilizes a 650+-fill down in it's construction. 650 and 800 are similar warmth... 800 is just a little more lofty for a given volume. Secondly, the Sub Zero SL utilizes a DWR coupled with a Conduit SL waterproof/breathable laminate throughout the jacket making for phenomenal weather protection. The Marmot uses a DWR (durable water repellent finish) on the outside of the jacket only providing a little less protection. The last difference is the price... $360 for the Marmot Jacket and $280 for the Mountain Hardwear Sub Zero SL. I hope this info helps!