Hi there. I'm about to purchase a 2019 27" imac and wondering if the upgrade from 9th gen 3.7i5 to 9th gen 3.6i9 is worth the nearly $400. Also, I will likely be going with a 3TB fusion drive--would that render the increase in i9's performance moot? Also, I don't do any gaming so don't need performance increases for that. But I do plan to keep the machine for 5-7 years and thus want to keep it fresh for longer. Thanks for your thoughts.