Well its done! The T9300 is in and macOS Sierra is running smoothly on my 2007 iMac. It does benchmark a little less than the X7900 but the T9300 runs much cooler. I will like to give it more time before I say for sure but I am thinking that it runs macOS better than the X7900.
Im not experiencing beachballs or lags like I was on El Capitan.
If anyone wants any more info just let me know. Im gonna work on it a few days and see how the experience is all around. And then do a final impressions in about a month