We do not know the chassis changes. All ford states is "a modified chassis." Modified could go many ways. The SN95 was a modified or heavily tweaked Fox chassis. Yes, yes, a new chassis would have been nice, but what it comes down to is money. With governments and politicians pushing for EV's...
I am not able to get a mustang, but I would go to the s650 from the s550. The reason would be the look. I am absolutely mesmerized by the car. The addition to the extra power, the tech, and the steering upgrades are big pull factors too