Like you, I've been replacing some old hunting clothing and purchasing upgraded clothing. I chose First Lite. The merino wool is great and much better than polyester. They have Cocona technology, which you can read about. First Lite had a problem originally with their Kanab pants in that they were not cut more generously in the legs, thighs and rear end. They solved that problem. With the exception of First Lite's Sanctuary jacket, most of their clothing are meant for the "active hunter," not stationary hunters in very cold conditions. First Lite's clothing, some of the reviews say, will keep you comfortable, while stationary, in 20-30 degrees. That said, here was my approach. I purchased several of their garments for western hunting and warmer mid-west conditions. I plan to use the old stand by, cold weather heavy wool apparel for mid-west very cold conditions.
As far as durability goes, I cannot speak to that. In Illinois where I hunt, there are a lot of briar patches. I've refused to wear my First Lite Storm Tight jacket and pants, Uncompahgre Puffy jacket and North Branch soft shell clothing into the Illinois woods because I don't want to damage them given their cost. I do, however, wear the First Lite merino wool top layers and plan to wear my Kanab pants in the Illinois woods.
The wool layering tops and Kanab pants (rip stop woven marino wool are very durable I'm told). Although I haven't worn my Kanab pants into the Illinois woods, only worn my wool tops, I plan to this year. They dry quickly, pull moisture from your body and wear very well.
I don't know if this fully answers your questions, but I hope so.