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I am willing to bet that changing 300,000 anchor text links will result in a penguin attack.

It's a bit hard to say really without having experienced the exact situation/problem/solution so unless you think you are getting penalized for it I would probably leave it alone, after all many say that S.E's only count one link per page if there are multiple identical URLS. All the best.

I can't say that it would be better or just the same.  I know that I would definitely try it and see what happens.  That's a lot of SEO, trying things out see what happens.  If it works, continue down the path, if it doesn't change course.