I must have missed her in me3 then I've seen more then one banshee on earth near the end but I don't remember one named morinth ah ok I've just seen but just don't remember because it's been awhile since i've played just now looked on me3 wiki.
She is between the first banshees you find in the monastery if you choose her in ME2(although she can appear during your mission on the Leviathan DLC,if you didnt gone to the monastery first) which probably means that she is the reason of the Reapers found about the monastery,since Banshees can only be made from Ardat Yakshi,however you discover that there are way more Ardat Yakshi who travel hidden in the limits of asari space,which probably was thought as a way to cover the hole if you picked Samara over Morinth.
Personally i go after Samara,the tragedy under her story make her a bittersweet character,and you can romance her without suffering any consequences since the conclusion only happens in ME3 IF you didnt picked one of your other romances.
Did this once,worth the try,although i still prefer Tali,i love Liara,and learned to like each of the romance options in the ME series,but the girl on suit has the special place among all of them.