So why go for XNM then if its tougher to remember???
Because XEM (or "eX-Economy-Movement") doesn't represent the idea of NEM, imo. NEM is a "New economy movement" and there is no key word "New" in XEM, but just, well,.. some "Economy Movement".
And in XNM we do have a word "New". Besides the combination of words "NM" sounds just like "NEM".