Iowa Cold Weather Layer - Bibs vs Puffy

[IAHunter1234]

I hunt in Iowa where temps can be anywhere 20 degrees down to -10 degrees. I have a set of Bibs that are fine but heavy. I mainly go during Muzzleloader season or 2nd shotgun with my dad and brother. We do sit in the morning and times will push to each other where some walking does happen and then sit for 2-3 hours late afternoon. Recently I have been buying some sitka gear and a black ovis puffy. I also have the cabelas space rain gear. I've been using the sitka gear creating my own layering system and am undecided if this best suits for extreme cold. Typically I am good down to 15-20 degrees sitting. I like the layering system for the ability to take it on and off when I walk in to my sit and take off if I know I am going to do walking for a while.

My question is do I keep my bibs for extreme cold weather. I just do not like how heavy they are and how unpackable they are and fill my bag up. While I have yet to try my black ovis puffy pants paired with the rain gear in this weather to compare the warmth, I am looking for suggestions to anyone that has tried this set up and the warmth compared to bibs. Wearing puffy gear paired with rain gear, is that similar warmth to bibs? I have looked at finding quieter rain gear than what I have, maybe sitka downpour? But do not want to spend that amount if it is not as warm as bibs in extreme cold. I typically am warm upper body but my legs can at times get cold. Would the Sitka Aerolite blizzard pants be another good option? May mismatch color a little as I dont feel I need to spend on a jacket but wanted to get everyone's opinion. Thanks