I have the KUIU Yukons and Kutanas and love them both. The Kutanas work well in the early season. They breathe and protect well. I have hunted with guys using some lesser brands and they have switched to KUIU after comparing our experiences. I cant speak to the Sitkas.
I have the Ascents. Haven’t used them in the field yet but make sure you look at multiple pics so you can get a true idea as to how little they are. I’d recommend doing a google image search and seeing a few pics of them on actual boots. Had I not got them on clearance, probably would not have purchased.
I had a pair like this from OR that I loved. Bought the FL version and could not get them to close on any of my size 13 boots apart from trail runners and merrell Moab’s.
I had an issue with Sitka thunderheads as well. They barely fit my books and were squeezing my calves. Sitka redesigned them and increase the size for 2019. New ones work and fit great. Not sure if they tweaked the ascent gaiters too.
I like my Kuiu Scree which are really similar to the original OR flex tex. Have not used the new Sitka ascent gaiter. First Lite is a waste of money unless your boots and feet are tiny, they are better suited to small feet with tennis shoes. These are short gaiters with little to no protection from moisture but they work extremely well to protect the bottoms of your pants and also to keep stuff out of your boots.
I have the original Sitka Stormfront gaiter. They work awesome for me and keep me mostly dry. The cover my foot all the way down to my first lace by my toe and fit my huge calf’s. I think think they have two sizes and mine are the larger of the two. My calves do sweat in them but when I need them the sweat isn’t near as bad as getting soaked calves and socks form dew or snow.
I also wear them in snake country to keep cheatgrass out of my socks and laces also for a piece of mind with snakes. I have some OR that just cover to the top of the boots like the ascents and IMO they are a waist of time to use for moisture, I find most wet brush which is where you get most of your moisture is about knee high so the short gaiters do nothing to keep you dry. They work well in the snow to keep it out of your boots though or to keep crap out of your socks and laces.