I certainly agree that Howling Banshees should be capable of damaging tanks, so the MW option is definitely not one I would like to see pursued.
I'm not in favour of the ignore cover option either, it makes them too effective against against the wrong sort of opposition in my opinion.
Neither do I want to see their armour save increased, since Striking Scorpions have always meant to be more durable.
I really like the idea of making them infiltrators though, as this would represent their ability to leap acrobatically over other units, and move at high speed very well, thus giving them some useful advantages over Striking Scorpions, so if Eldar players want to test anything, I think this would be a very good change to try out (although I'm sure some of the veterans on this forum probably already have).
One final brief word, this time on Harlequins, one of the best things about Epic EA is that they are not part of the Eldar army list, as it resolves a whole heap of background issues in one go, so I would encourage them to remain separate (and yes, I have Space Marine edition Harlequin stands, so I am disadvantaging myself, before anyone asks

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Soñando con una playa donde brilla el sol, un arco iris ilumina el cielo, y el mar espejea iridescentemente.