Excellent exploration of the issue. I, for one, think the Doctor made the right choice. As we saw in FotD and TL, Donna can be amazing without the Doctor, and I have faith she will be. But such a cost to both of them! Donna, at least, can't miss what she doesn't remember; the Doctor, however, will miss her terribly.

BTW, I find your page hard to read, with the small print and gray-on-white typeface. Just FYI, but you might want to think about changing it. For great justice.