Investors and founders have had to become more creative and seek other ways to exit ($$). Only a handful of companies have made it through the SOX morass. So, it does seem logical that they are better. But, to suggest SOX might have actually been positive? Like the TSA is positive because more people are learning to fly? (I don't know if this is true).
Multinational I work for with over 100 billion yoyos of revenue and 150,000 employees stepped off the NYSE because SOX was too expensive to be bothered with.