If not remembering it makes it not matter, nobody can remember anything after they die, and everyone's going to die, wouldn't that mean nothing matters?
My answer is that there's no persistent her. The past is every bit as real as the present, and the her from the surgery is just as real as the present her.
Would you pay $10 to have [extremely pleasant experience of your choice] for one hour, but have all the memories of it erased immediately afterwards?
http://www.smbc-comics.com/index.php?db=comics&id=2705
Addresses questions like "If I don't remember, but it definitely happened... who suffered?" in a rather non-obvious way (non-obvious to me, anyway).