I just bought the same machine. iMac 27 with 780 graphics card. I was able to get AE comps dynamically linked to premier pro CC. My first mistake was not having the CC version of all the adobe software. Trying to link PP CS6 to AE CC will not work. It has to be PP CC. Once I did that my AE comps dynamically linked to PP. I did notice that even though those links appeared in PP, they were having issues like very slow render. For me, just simply going back into AE and back to PP again did something to the comp in PP. It’s like it wakes the comp up and it renders fast. So I basically finding myself switching back and fourth between AE and PP to wake up that comp. Soumds crazy but it works.