SX6000 Pro for consumers is indeed better than the MX500. As is the 660p.
He accidentally switched tiers 4 and 5. The sx6000 pro/ex900/mushkin helix-L etc. are better than the 660p/P1.
Another one that's not really that relevant to this discussion but i'll add now anyway are that the Phison E12 based drives (sabrent rocket, inland premium, corsair mp510, mushkin pilot, silicon power A80 etc.) should be in tier 2.