This is my American girlfriend's name, I love her and she fits with it well. The vibe i get is kinda motherly/feminine but also like a lil stern and strong but feminine, and a tad unique. I really like the spelling it really adds to the feminine compared to Morgan in my opinion. But I do come from Sweden where Morgan is strictly a male name so that may be why.
I like the idea of Morgen being spelt with an "e" rather then an "a". It gives the name a different look but it also gives the name a whole other meaning if you take the Dutch or German meaning of "morning". A person who's name is spelled this way separates themselves from all the other Morgans in a way.