Now, regarding Adi's death: I'm one of the guys who's constantly going "TCW didn't ruin anything; all they've done is added." While Adi's death does break with that a bit, I don't think it removes Obsession from continuity.

Personal Retcon Ahoy:

Obsession takes place slightly earlier in continuity (I'm thinking shortly before the S3 time-jump, before the events of the Nightsister trilogy). Adi didn't die, she was just terribly wounded and got better (I don't remember how she died, but as long as she wasn't torn apart or burned in a fire, then a comic-book-resurrection is ok). And when Ventress leaves the Galaxy forever, it just isn't forever. She comes back, and returns to Dooku, who betrays her for the last time, causing her to run to Mother Talzin (Nightsisters trilogy).

If I remember Obsession correctly, she just got stabbed in the chest by General Grievous - it is certainly possible that she could have survived this (after all, Darth Maul survived being cut in half).

It was meant to be blood, but Maul was meant to die as well. Maybe Talzin used some red magic on Maul the first time... haha

As someone who has seen that exact injury in the trauma department at a hospital (admittedly with a knife rather than a lightsaber), that is in fact quite survivable. So long as you miss the heart and the aorta, you're not going to kill the person. Especially with a lightsaber that would cauterize whatever else it damaged.

Well Kyle Katarn and Jaina Solo both got stabbed through the chest and survived so it's not beyond the realms of possibility