I have the original kenai pants, and both versions of the superdown pants. I tried and sold the Kifaru LPP pants and the FL Uncompaghre pants.
The kenai are quiet but not wind resistant and the least warm. They are nice to move in due to breathability. Also the most comfortable next to skin if you use them in place of a base layer
The superdown ultra I have the least time with. They seem like they will be a great layer for sitting in wet environments under a pant or rain gear. They have a harder slicker shell, less comfortable than the kenai next to skin. Significantly warmer than the kenai and more wind proof but less breathable. I would not hike far in these.
The superdown pro I have used most. They are warm and have been durable enough. I have the matching jacket and they work for my late season rifle hunts for whitetail plus western hunts. The set I’d have if I was to only have one. I have oversize Chugach rain pants that have enough stretch to be comfortable hiking in despite being a bit baggy, but plenty of room to fit over the superdown pro pants. In some conditions this is perfect. I use the pro pants like many would use the ultra.
The kifaru are great, just not a great fit for me. They fit more like a regular pant for me and I’d prefer a bit baggier fit to go over other layers. Very durable seeming and well made. I have the LPP jacket and it’s been great. Used in AK twice and several other states. I also use a Kifaru Slickbag. The best synthetic in my opinion.
The First Lite just did not seem warm enough to me to beat out the others. I rated it as only slightly better than my original Kenai pants, not as warm as the superdown ultra. Not close to as warm as the LPP or superdown pro. Less wind resistant than any but the kenai also. Well made, light, great fit, but just not for me due to warmth.
Hope this helps. That’s the one’s I’ve used and my thoughts.
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