Hi. I am debating between getting 2 iMacs. The top tier one with the 256 ssd and the i7 processor upgrade or a refurbished one with a 3 tb fusion, I7 processor, and the NVIDIA GeForce GTX 780M graphics processor with 4GB of GDDR5 memory memory. I don't need the extra storage on the fusion and heard that it is slower, which is what I am worried about. The graphics processor upgrade is nice but would it be worth the tradeoff? Thank you !