I recently tried to establish a romantic relation with LSE and EIE. Neither worked. LSE is pretty usefull and great for friendship, but him underestimating my Ti was driving me crazy. And I didn't value his Te explanations enough. I guess it's a metter of personal life expirience, I am used to SLE and discussions over Ti, so I felt like it's almost what I want but not there and it was getting me irritated. While he is used to people taking what he says for granted and was annoyed by me arguing. Another thing is too much Si - LSE takes it too seriously, like it was his job to take care of me, ESE would do it as a kind of joke or gesture, not undermining my ability to care of my self.
With EIE I have a great time, it's pure fun. But I can get his full atention only when showing at least a shadow of Se and only then I get some Si. Kind of a lack of Si I get as a lack of attention even though I get loads of Fe, then I get confused and mistrustful. Classical problem of semi-dual not turning into dual.
Summarisng, mirage is more stable, semi-dualship more exiting and more likely for a romantic relationship - I don't know if it's only me, but I get attracted by Fe not Si (Si is assuring me about other persons feelings). Seems to me it depends on a type, person and what you expect, can't say that mirage or semi-dualship is better.