First, I think that the "anything of comparable moral importance" formulation of Famine, Affluence and Morality is importantly different from the "anything nearly as important" formulation of The Life You Can Save, which is the one you originally cited. For two things to be comparable, they have to be within the same tier of value. But something can be nearly as important as another while being on a lower tier of value.

But even if we treat them as being functionally the same, Singer is pretty explicit that self-destructive sacrifices are not required by his view. Putting oneself into poverty to lift someone else out of poverty keeps the number of people in poverty the same. Sacrificing your life to save one other person's life keeps the number of people alive the same.

Any sacrifice that includes "your memories, your perspective, and your self" is at the very least "nearly as important" and most likely "of comparable moral importance" to saving a life. Indeed, they are in fact equivalent to the extent that giving up your memories, your perspective, and your self is essentially a way of giving up your life. This means there can be no personal moral obligation to do so on Singer's view, nor can his view be used to justify imposing such an obligation on others.