I've only worn mine when it's cold and is a lot less itchy after they are laundered! I have the light weight hoodie and its one of my favorite hunting shirts, especially for tree stand hunting!
I have worn the core 4 clothing for 3 years. I wear the 190 merino long sleeve shirts and the 290 mid layer and the 190 beenie. If you launder them before wearing there is no itch problems that I have noticed at all. In the past I was never able to wear wool at all but the core 4 sutff doesn't bother me any more than the First Lite.
I have the Kuiu stuff and it is super soft. I have the 125 and the 145 weight and the 125 is the softest shirt I own. I'm getting another 2 just to wear around town.
The c4e merino I bought a couple of years ago itched terribly and shrank at least a full size after washing. (Yes, I washed in cold and air dried). Trying contacting c4e for a refund or exchange and they could've cared less. Will never buy another c4e product again after that CS experience.
I've used 1st Gen KUIU, Smartwool, First Lite, and Sitka. First Lite being my favorite of the bunch in terms of how it feels and performs.
1st Gen KUIU is also good, but they have since moved to the blended stuff that I have not tried.
I've worn it for several years and no itching issues. Bought a First Lite short sleeve shirt this year and for me there is not difference between the two.
I have 5 merino wool tops from them and beyond the hoodie being a athletic fit all are great and comfy, no itch here. Everything is sized the same except for the hoodie. All bought 2-3 years ago.
I just got back from my Moose hunt on which I used the C4E and KUIU. The C4E is not as soft as the KUIU but I noticed no itch from either and could not tell if one was better than the other. I do like the fit of the C4E better as the KUIU seems wide and not an athletic fit.
I have some C4 base shirts bought back before easton bought the company. Softest merino I have ever worn, feels like fleece its so soft. Today, I would go with firstlite, unless KUIU has fixed the sizing problems, then I might go that route.