Usually there is no answer to a question that says "what happens if I use the device outside the spec?" The spec is there for a reason and that is how the device is tested. You can do your own characterization and share with the forum but I would be very surprised if Cypress or for that matter any other vendor would tell you you can use the part with 3x overclocking.
Sorry pal, if 2 MS/sec are required, you might need a stand alone ADC.
It is like a sign telling "Keep off the Grass", you'll never be able to tell beforehand what will happen if you put up a tent there, but you can be darn sure that it will come out for nothing good...