I've used the sitka ambient hoody from the beginning of the September straight through till now as a replacement for my heavyweight core that I somehow lost. Very versatile piece that's applicable to all weather conditions, moves heat well while moving and keeps you warm while static. Fit is perfect with a few exceptions, I'm not a fan of the tight cuffs in the sleeves as I do like to roll them above my elbows when overheating and it's more difficult to do this with the cuffs. Durability is better then the heavyweight as that piece pillared after just a few washes, however the ambient has a few threads pulled from busting brush which never happened with the heavyweight. Also found the ambient to hold smell quicker then the heavyweight after a day or 2 of heavy hiking, where as the heavyweight core would start to smell after the 4th day