Having owned a 2018 5.0 a10 fully loaded (traded due to transmission failure at 7k miles). I can say the mustang is indeed faster and better handling, but that is extremely limited by weather. Also, the stinger handling isn't that bad, I do have wider 245/275 wheels on dws currently. Obviously magnetic suspension will be better and it's a 2 door car. The weather is what people never think about too cold or wet pavement you can forget your 3.9s 0-60 and 12 s 1/4 mile. I beat a new ctsv with my stock awd gt2 because his tires wouldn't get any traction due to it being 45°F outside. Both have their ups and downs. I miss the power, sound and technology of the mustang for sure, but the stinger has more comfort and practicality plus drivable in all weather without being afraid of dying.
Also, the reliability of the mustang was a joke and it sat at the dealership for almost 4 weeks and the trans had to be rebuilt. Ford would not lemon law it. After that I had no trust in that car and definitely didn't want to deal with that after my warranty expired. The repair under warranty was around $6,000, so if you're not under warranty get ready for that possibility. My stinger has lifetime power train and 10 year bumper to bumper.
Also, the reliability of the mustang was a joke and it sat at the dealership for almost 4 weeks and the trans had to be rebuilt. Ford would not lemon law it. After that I had no trust in that car and definitely didn't want to deal with that after my warranty expired. The repair under warranty was around $6,000, so if you're not under warranty get ready for that possibility. My stinger has lifetime power train and 10 year bumper to bumper.