So, just my two cents here, but for me, iMacPro1,1 performs way better than iMac19,1. I'm also running a 9900KS with Vega 64, and I mostly use it for Davinci Resolve. All my exports were a lot slower in iMac19,1 compared to iMacPro1,1. Maybe it's different for you if you mainly use Premiere and...