While I did not have GT350, I traded my 2013 Boss 302 for a 2020 GT500 fully loaded without the Recaro seats. I will say I do miss the manual transmission. Don't get me wrong the 500 is light years ahead of the Boss and will be a big jump in power to your 350, but if you love the experience driving the manual you may miss that part of the driving experience.Well its all in place. After some....speaking back N fourth, the final deal was put in place, numbers crunch, and options available. Now I decide yay or nay. Brought all the paper work home and I'll go through. Have to say it has been a interesting process.
For Track use the 500 with those instantaneous shifts will dominate for sure.
For your weekend canyon carving, you may miss the manual. Even in manual mode in my 500 I miss the connection with down shifting and rev matching manually. Made the car more engaging for me.
You will not be disappointed in getting a 760HP car with a full engine warranty that can be upgraded even more as needed.
Heck just keep them both. lol