To get back to topic - the question is comparing ITALIAN westerns with JW westerns - I think Ethan is as close as Wayne could come to the Italian Man With No Name. Yet the major difference is of course this:
The regular, pure western hero of the US, even when he is half good/half bad, as Ethan is, or Jimmy Stewart's bounty hunter in The Naked Spur, to name another example, there is always the transition during the film. He might start out as the bad man (like Robert Hightower) but in the end, he will fight for the right cause.
The classic American anti-hero is Bogart, and his trademark sentence is "I stick my head out for nobody" - yet that's exactly what he is going to do in To Have and Have Not and so many others.
It's different with the screen persona of the spaghetti western - and Clint just made three of them, mind you - there was an avalanche of Italian westerns yet only very few made it do the English spoken market. So the Django-films or the numerous westerns with Guiliano Gemma really defined that genre more than the 3 ones with Clint (when Clint brought that persona to the American western with Hang Em High, it was already a fusion between the two: because in the end this man sided with the law). The difference between the Man with No Name and the American western hero (no matter how brutal his methods) is always this:
The spaghetti westerner lives by his own code, makes things happen just for him, not for society. And to win he fights dirty and breaks every code of the west, only to stay alone in the end, take his winnings and take off! (like he does in all the Dollar-westerns) So, essentially, he DOES NOT CHANGE (finally, I come to the point!) during the film as, for instance, Ethan does or the tougher Jimmy-Stewart-characters do, or even the Italianwestern-influenced Dean Martin in Bandolero!, he is the same in the end (The Good, Bad & Ugly even ends with the same situation as they started out).
Those situations worked so well for Leone in Once Upon a Time because those characters didn't need to change - from beginning to end. Bronson doesn't change. Fonda doesn't change. All there is are those huge close-ups of faces without any emotions at all. Morricone once said it was so much fun to do the music because the Leone-characters were like cartoon-characters.