I’ve never had issues with Arko. It’s a recent discovery for me and it’s quickly become one of my favorites.
My last shave with it and the Mach 3 was irritation free. With DE I’ve basically had irritation on my neck every time no matter what soap or blade I use.
If you are getting neck irritation, either you are having trouble with your shave soap or your shaving technique. Unless you have a skin condition that requires treatment by a medical professional, eventuallly you should be able to get an irritation-free shave. It took me a few years of practice and evaluation of several dozen shaving soaps before I was finally able to shave with zero irritation. I now get an irritation-free shave nearly every time. However, if I make the mistake of going back to low end soaps, my face will regret it.