I like to pack the SD Pants on hunts that see temps in the mid 20s or lower. Not that mid-20s is all that cold, but having the down pants allows me to pack a light 30-Degree sleeping bag. If it's cold at night I wear the down pants in my bag to stay plenty warm. Then the pants are available during the day to throw on while glassing. In my experience they're actually not too hot to wear as a mid-layer while hiking if the temps are in the upper-teens. Everyone is different though.
With just over 1.5oz of down, this pant is still considered an active layering piece. They're not going to cook you alive by any means.
In the KUIU system, carrying a 30-degree bag and SD Pants only weighs 3oz more than the 15-degree bag alone, and that extra 3oz goes toward substantial versatility in around the clock temp regulation. Something to consider if you will be living out of your pack on your late season hunts.
