Tracktime is better, but I used auto x for a year or two before I did schools/opentrack at racetracks. Great way to learn limits of handling where going off you won't hit anything. I was fortunate in that I auto crossed with BMW CCA in San Diego and the auto x track was set up on the Qualcomm...
Yeah, the Tech Package was a $7,500 option on the 2016. My 2016 has the Tech Package. Your 2017 with an electronics package has the same equipment, plus the trans and diff coolers.
I'm a retired club racer (BMW CCA-E46 M3) and until I bought my 2016 GT350, I modified the crap out of all my Mustangs ('91 GT, '96 SVT Cobra, '99 SVT Cobra, and '04 Terminator). Maybe I am getting lazy, but my GT 350 handles GREAT stock. Unless you are trying to share a few tenths off of a lap...
FYI: Talked to the GM at Galpin Ford in Prescott about Galpin Ford in LA. Turns out that Galpin Ford in Prescott has always been owned by the Galpin family while Galpin Ford in LA was sold off by the Galpin family years ago. To the best of my knowledge, Galpin Ford in LA is the largest volume...
My 2016 wore the front tires down to the cords on the inner edges of both fronts by 10k miles. Had camber bolts installed and an alignment with no toe in or out and now no cording and have even wear. Does not handle quite as good, but my club racing days are over.