Hmmm, I just don't think the student (Isis) has overcome the teacher (Neurosis). I mean, Neurosis will always hold claim to more-or-less inventing the whatever-genre all these bands fit in, whether you call it noisecore, sludgecore, post-hardcore, etc.
Both bands did come from humble beginnings, releasing a few pedestrian albums, and then coming into their own. Neurosis just happened to do it first, and have been doing it longer, allowing them change identities a few times while always staying Neurosis.
And Neurosis has released 6 highly-praised albums. Isis has only released 2 (3 if you count Celestial, which IMO is average)