"Whether it was Pope or Eugenes, they both paid a great price in learning the Demon Book.
Both their bodily foundation and soul attributes changed because of the Demon Book.
Eugenes established the Church of Cannibalism within his body, united with the freely extendable Black Flesh Mountain, and even constructed a unique inner world. His future development is immeasurable... he is bound to surpass M.O. and achieve greater accomplishments.
Pope, on the other hand, connected to an evil star completely isolated outside the main world, adding a new attribute to his soul's plane.
He might eventually completely control this rejected evil star and gather it into the star brain.
The Count wants to learn the Demon Book, and he is bound to experience a different process. With his former Blood Brew physique, he definitely couldn't endure it... but now it's entirely different.