I love my '15 GT ... and I can get almost the same performance as a stock '18 with the Ford Performance PP2. That's a whole lot less than the first year depreciation on a new one. But then, it's only money.
I have a 2015 GT premium, auto so no PP. The car is not even close to floaty and handles very nicely. It's quite comfortable for street driving and it's braking performance is impressive. Unless you are going to track your car or drive like a maniac on the street, the non-PP car will please you.