I'm on my own for a few days with just my youngest, and have found myself doing a bit of a random rewatch. So many little connections tied up in the finale, it's really quite clever.
Just done the first Children in Need special, and it occured to me that Rose/Bad Wolf resolution is very similar to the end for Donna - the Vortex was breaking her head, just as the TimeLord consciousness was killing Donna. They're both said to be in danger of 'burning up'.
Now, Nine absorbed the Vortex by kissing Rose, pulling it out of her (which then basically killed him so he had to regenerate). He couldn't do that with Donna because she hadn't taken something into herself that was separate like the Vortex, she had been part of a metacrisis with the Second Doctor and had been changed at a fundamental level. So all he could do was wipe her memories and sort of make the Time Lord consciousness dormant.
Now, watching Human Nature/ Family of Blood this morning, and also thinking about The Unicorn and the Wasp (the Agatha Christie episode) there are strong hints that, even though someone's memories may be wiped, little things will still bleed through (like John Smith doing the fancy throw with the cricket ball, and Agatha Christie recalling odd bits from her adventure with the Doctor). So, I'm actually thinking that, although at first, because of the emo stuff, it's a very, very sad ending, it really needn't be.
Btw, next instalment to The Other side of the mirror, for them as cares, should be up later tonight.