I have both the Sub Zero and the Compressor PL. If you want compressible warmth, it will absolutely be the Compressor. It packs down to fit inside 3/4 of a 1L Nalgene bottle, the Sub Zero when packed all the way down is 6"x9". If you do anything active at all besides stand around outside in the Sub Zero, you will literally sweat your balls off no matter how cold it is outside. The Sub is just sickening warm. The Compressor is also extremely warm for how light and thin it is. I would say with a lot of confidence that for it's weight, 15 oz, it is the warmest jacket of it's kind out there. Primaloft really is superior in warmth to Mountain Hardwear's synthetic insulation Thermic Micro. The material used with the Compressor is highly, highly wind resistant. Highly. The material used with the Sub Zero is very tough for a down jacket. Both will last you at least 3 years with significant wear. My Compressor has survived at thruhike of the AT and it's still in very good shape. Mountain Hardwear is just a great company. Bottom Line: The Sub Zero will keep you HOT in Sub Zero weather. Truly. The Compressor will keep you WARM in sub 20's.

I have this jacket and I wear it in the winter as my main parka. It seems to do very well with temps below freezing. I typically need to put a base layer on (besides a tshirt) once it gets lower then 10 F. I have not owned the compressor but looking at it in the store I can't imagine it would be very warm. The insulation seems thin. Get the sub zero and add some nikwax to the shell to help shed the rain if it gets above freezing. I truly love my coat. Wear it all the time.