For the record, I do not believe Calvinists are cryto-Valentinians. I do not believe Calvinists are Gnostics, so please understand my question knowing I am not trying to paint anyone in a good or bad light.
What specific beliefs do Calvinists (or proto-Calvinists like Augustinians) specifically take issue with in Valentinian's predestinarian system?
So far, I've only been able to find that the Valentinians believed there were three different classes of men with different natures. I believe Calvinists teach that the saved and the damned have the same human nature, but I'm not sure.